/* --- START OF FILE style.css --- */

:root {
  --primary-color: #5a2e98;
  --primary-color-darker: #6b3aa7;
  --secondary-color: #f0f0f0;
  --text-color-dark: #333;
  --text-color-light: #fff;
  --background-light: #f0f0f0;
  --background-dark: #222;
  --box-shadow-color: rgba(0, 0, 0, 0.1);
  --border-color: #ccc;
  --font-family-primary: 'Times New Roman', serif;
  --font-family-secondary: 'Arial', sans-serif;a
  --gold-color: gold;
  --error-color: #ff4d4d;
  --link-color: #5a2e98;
  --link-hover-color: #333;
  --star-color-inactive: #ccc;
  --star-color-active: #ffc107;
  --login-bg-start: #ee7752;
  --login-bg-mid1: #e73c7e;
  --login-bg-mid2: #23a6d5;
  --login-bg-end: #23d5ab;
  --login-form-bg: rgba(0, 0, 0, 0.85); /* Slightly less transparent for readability */
  --login-form-hover-shadow: 0 10px 20px rgba(0,0,0,0.4);
  --login-form-shadow: 0 5px 15px rgba(0,0,0,0.3);
  --login-input-bg: rgba(255, 255, 255, 0.15);
  --login-input-focus-bg: rgba(255, 255, 255, 0.25);
  --login-button-bg: #6200EE;
  --login-button-hover-bg: #7c4dff;
  --popup-bg-light: rgba(255, 255, 255, 0.95);
  --popup-bg-dark: rgba(40, 40, 40, 0.95);
  --nav-height-desktop: 10rem; /* Approximate */
  --nav-height-mobile: 7rem; /* Approximate */
}

/* --- Global Styles & Resets --- */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  font-family: var(--font-family-secondary); /* Use secondary as default, override where needed */
  background: linear-gradient(-45deg, var(--login-bg-start), var(--login-bg-mid1), var(--login-bg-mid2), var(--login-bg-end));
  background-size: 400% 400%;
  animation: gradientAnimation 15s ease infinite;
  color: var(--text-color-light);
  position: relative;
  transition: background-color 0.5s ease, color 0.5s ease;
  overflow-x: hidden; /* Prevent horizontal scroll */
  display: flex; /* Added for centering container */
  justify-content: center; /* Added for centering container */
  min-height: 100vh;
}

body::before {
  content: '';
  position: fixed; /* Changed to fixed */
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.5); /* Dim overlay */
  z-index: -2; /* Behind content and nav */
}

@keyframes gradientAnimation {
  0% { background-position: 0% 50%; }
  50% { background-position: 100% 50%; }
  100% { background-position: 0% 50%; }
}

.container {
  width: 90%;
  max-width: 1200px;
  margin-left: auto;
  margin-right: auto;
  position: relative;
  z-index: 1;
}

img {
  max-width: 100%;
  height: auto;
  display: block;
}

a {
  color: var(--link-color);
  text-decoration: none;
}

a:hover {
  color: var(--link-hover-color);
  text-decoration: underline;
}

button {
  cursor: pointer;
  font-family: inherit;
}

ul {
  list-style: none;
}

h1, h2, h3 {
  font-family: var(--font-family-primary);
  color: var(--text-color-light); /* Default white for headings */
  text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.4);
}

h2 {
  font-size: 1.8rem;
  margin-bottom: 1.5rem;
  text-align: center;
}

h3 {
  font-size: 1.2rem;
  margin-bottom: 0.75rem;
}

/* Visually Hidden Utility */
.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* --- Dark Mode --- */
body.dark-mode {
  background: var(--background-dark);
  color: var(--text-color-light);
}

body.dark-mode::before {
  background-color: rgba(0, 0, 0, 0.7); /* Darker overlay */
}

body.dark-mode #main-nav {
  background: rgba(0, 0, 0, 0.2);
  box-shadow: 0 2px 5px rgba(255, 255, 255, 0.1);
}

body.dark-mode #main-nav.scrolling {
    background: linear-gradient(135deg, rgb(28 15 48 / 87%), #000000);
    box-shadow: 0 2px 10px rgba(255, 255, 255, 0.2);
}

body.dark-mode #main-nav:hover {
  background: linear-gradient(135deg, rgba(17, 82, 106, 0.8), rgba(107, 58, 167, 0.8));
}
body.dark-mode #main-nav.scrolling:hover {
  background: linear-gradient(135deg, rgba(17, 82, 106, 1), rgba(107, 58, 167, 1));
}

body.dark-mode #main-nav .submenu {
  background-color: rgba(20, 20, 20, 0.9); /* Darker submenu */
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.5);
}

body.dark-mode #search-box {
  background-color: rgba(255, 255, 255, 0.15);
  color: var(--text-color-light);
  border: 1px solid rgba(255, 255, 255, 0.2);
}
body.dark-mode #search-box:focus,
body.dark-mode #search-box:hover {
  background-color: rgba(255, 255, 255, 0.2);
  box-shadow: 0 0 0 2px var(--primary-color);
}

body.dark-mode #search-button i.fas.fa-search {
  color: var(--text-color-light);
}

body.dark-mode #search-suggestions {
    background-color: #333;
    color: var(--text-color-light);
}
body.dark-mode #search-suggestions li {
    color: var(--text-color-light);
}
body.dark-mode #search-suggestions li:hover {
    background-color: #444;
}
body.dark-mode #search-suggestions .no-results {
    color: #aaa;
}

body.dark-mode .book,
body.dark-mode .carousel-item {
  background-color: rgba(255, 255, 255, 0.05); /* Subtle background */
  border: 1px solid rgba(255, 255, 255, 0.1);
  box-shadow: 0 2px 5px rgba(255, 255, 255, 0.05);
  color: var(--text-color-light);
}
body.dark-mode .book h3,
body.dark-mode .carousel-item h3 {
  color: var(--text-color-light);
  text-shadow: 1px 1px 1px rgba(0, 0, 0, 0.7);
}
body.dark-mode .book p,
body.dark-mode .carousel-item p {
  color: rgba(255, 255, 255, 0.8); /* Slightly dimmer text */
}
body.dark-mode .book .book-publication-date {
    color: rgba(255, 255, 255, 0.7);
}

body.dark-mode .pagination button {
  background-color: #444;
  color: var(--text-color-light);
  border-color: #666;
}
body.dark-mode .pagination button:hover:not(:disabled) {
  background-color: var(--primary-color-darker);
}
body.dark-mode .pagination button:disabled {
  background-color: #555;
  color: #999;
}

body.dark-mode .form-container {
  background: rgba(0, 0, 0, 0.8); /* Dark form background */
}

body.dark-mode .book-details-content {
  background-color: rgba(255, 255, 255, 0.08);
  color: var(--text-color-light);
  border: 1px solid rgba(255, 255, 255, 0.15);
  text-shadow: 1px 1px 2px rgba(0, 0, 0, 0.5);
}
body.dark-mode .book-details-content h2,
body.dark-mode .book-details-content h3 {
    color: var(--primary-color); /* Keep primary color for contrast */
    text-shadow: 1px 1px 1px rgba(0, 0, 0, 0.7);
}
body.dark-mode .book-details-content p {
    color: rgba(255, 255, 255, 0.9);
}
body.dark-mode #book-details-comment-box {
    background-color: rgba(0, 0, 0, 0.3);
    color: var(--text-color-light);
    border-color: rgba(255, 255, 255, 0.2);
}
body.dark-mode #book-details-publication-date.book-publication-date {
    color: rgba(255, 255, 255, 0.7);
}
body.dark-mode #close-book-details-button {
    color: #ccc;
}
body.dark-mode #close-book-details-button:hover {
    color: #fff;
}
body.dark-mode .book-info p .info-value,
body.dark-mode #book-details-description .info-value {
   color: rgba(255, 255, 255, 0.8);
}
body.dark-mode #payment-popup .payment-instructions p {
    color: rgba(255, 255, 255, 0.8);
}
body.dark-mode #payment-popup .account-info p {
        color: rgba(255, 255, 255, 0.8);
}
body.dark-mode .tertiary-button {
    color: #bb86fc; /* Material Design purple */
}
body.dark-mode .tertiary-button:hover {
    color: #d1a9ff;
}
body.dark-mode .favorite-button.active i {
    color: #cf6679; /* Material Design error color */
}


body.dark-mode .site-footer {
  background: rgba(0, 0, 0, 0.15);
  box-shadow: 0 -2px 5px rgba(255, 255, 255, 0.05); /* Top shadow */
}
body.dark-mode #newsletter-form input {
    color: white;
    background-color: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
}
body.dark-mode .footer-bottom a {
    color: #bb86fc; /* Consistent link color */
}
body.dark-mode .footer-bottom a:hover {
    color: #d1a9ff;
}

body.dark-mode #payment-popup,
body.dark-mode #ve-chung-toi-popup,
body.dark-mode #newsletter-notification-popup {
  background: var(--popup-bg-dark);
  color: var(--text-color-light);
}
body.dark-mode #ve-chung-toi-popup {
    background-color: rgba(30, 30, 30, 0.97); /* More specific dark bg for letter */
    color: #eee;
    border-color: #555;
}
body.dark-mode #ve-chung-toi-popup h2 {
    color: var(--gold-color); /* Gold title in dark mode */
}
body.dark-mode #ve-chung-toi-popup #close-ve-chung-toi-popup {
    color: #aaa;
}
body.dark-mode #ve-chung-toi-popup #close-ve-chung-toi-popup:hover {
    color: #eee;
}
body.dark-mode #payment-popup .account-info .account-number,
body.dark-mode #newsletter-notification-popup a {
    color: var(--gold-color); /* Keep gold consistent */
}
body.dark-mode #payment-popup-close-icon,
body.dark-mode #close-newsletter-popup-icon {
    color: #bbb;
}
body.dark-mode #payment-popup-close-icon:hover,
body.dark-mode #close-newsletter-popup-icon:hover {
    color: #fff;
}

body.dark-mode #starfield-sky {
  display: block; /* Show stars only in dark mode */
}


/* --- Header (Desktop - kept minimal as nav takes over) --- */
.site-header {
  display: none; /* Effectively hidden by the fixed nav */
}

/* --- Main Navigation --- */
#main-nav {
  background: linear-gradient(135deg, #11526a, #6b3aa7f0);
  color: var(--text-color-light);
  padding: 0;
  border-radius: 0;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 100;
  display: flex; /* Keep flex for the container */
  /* align-items: stretch; Let container handle height */
  justify-content: center; /* Center the nav-container */
  height: auto; /* Adjust height based on content */
  width: 100%; /* Full width initially */
  transition: background 0.5s ease-in-out, box-shadow 0.5s ease-in-out;
}

#main-nav .logo {
    border-radius: 50%;
    object-fit: cover;
    border: 1px solid rgba(255, 255, 255, 0.15);
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
    transition: all 0.3s ease;
}

#main-nav .logo:hover {
    transform: scale(1.05) translateY(-2px);
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.4);
    border-color: rgba(255, 255, 255, 0.4);
}

/* This container centers the content on desktop */
#main-nav .nav-container {
    width: 90%;
    max-width: 1200px;
    /* margin-right: auto; */
    display: flex;
    flex-grow: 1;
    justify-content: space-evenly;
    align-items: center;
}

#main-nav:hover {
  background: linear-gradient(135deg, var(--primary-color-darker), #50288a);
}

.nav-section-left {
  display: flex;
  align-items: center;
  padding-left: 20px; /* Desktop padding */
}

.nav-section-left .logo {
  max-width: 120px; /* Adjusted size */
  height: auto;
  transition: transform 0.3s ease;
}
.nav-section-left .logo:hover {
  transform: scale(1.05);
}

.nav-section-right {
  display: flex;
  flex-direction: column;
  align-items: flex-end; /* Align content to the right */
  padding-right: 20px; /* Desktop padding */
  justify-content: center; /* Vertically center content rows */
}

.nav-sub-flow-top,
.nav-sub-flow-middle,
.nav-sub-flow-bottom {
  display: flex;
  align-items: center;
  width: 100%; /* Ensure full width within right section */
  justify-content: flex-end; /* Default to right align */
  padding: 5px 0;
}

.nav-sub-flow-top {
  justify-content: center; /* Center the title */
}

.nav-sub-flow-middle {
  border-top: 1px solid rgba(255, 255, 255, 0.15);
  border-bottom: 1px solid rgba(255, 255, 255, 0.15);
  padding-top: 8px;
  padding-bottom: 8px;
  justify-content: center; /* Center the menu */
}

.nav-sub-flow-bottom {
  padding-top: 8px;
}

.nav-sub-flow-top .site-title {
  font-size: 2.3em; /* Desktop title size */
  color: var(--text-color-light);
  text-shadow: 1px 1px 3px rgba(0, 0, 0, 0.4);
  font-family: var(--font-family-primary);
  white-space: nowrap;
  margin: 0;
  text-align: center;
}
.nav-sub-flow-top .site-title:hover {
    transform: none; /* No hover effect needed */
}

#main-nav .menu {
  display: flex;
  align-items: center;
  justify-content: center; /* Center menu items */
  flex-wrap: wrap; /* Allow wrapping on potentially smaller desktops */
  gap: 5px 15px; /* Row and column gap */
}

#main-nav .menu > li {
  position: relative;
  display: flex; /* Ensure flex alignment */
  align-items: center;
}

#main-nav .menu > li > a {
  color: var(--text-color-light);
  text-decoration: none;
  padding: 8px 12px; /* Slightly smaller padding */
  border-radius: 5px;
  transition: color 0.3s ease, background-color 0.3s ease, transform 0.2s ease;
  display: flex;
  align-items: center;
  gap: 8px;
  font-family: var(--font-family-secondary);
  position: relative;
  overflow: hidden;
  white-space: nowrap;
  font-size: 0.95rem; /* Slightly smaller font */
}

#main-nav .menu > li > a::before {
  content: '';
  position: absolute;
  left: 0;
  bottom: 0;
  width: 100%;
  height: 2px;
  background-color: var(--secondary-color);
  transform: scaleX(0);
  transform-origin: center; /* Animate from center */
  transition: transform 0.3s ease;
}

#main-nav .menu > li > a:hover::before,
#main-nav .menu > li > a.active::before {
  transform: scaleX(1);
}

#main-nav .menu > li > a:hover,
#main-nav .menu > li > a.active {
  color: var(--secondary-color);
  background-color: rgba(255, 255, 255, 0.1);
  transform: translateY(-1px); /* Subtle lift */
}
#main-nav .menu > li > a i {
    font-size: 0.9em; /* Slightly smaller icons */
}

#main-nav .submenu {
  display: none; /* Use visibility/opacity for transitions */
  visibility: hidden;
  opacity: 0;
  position: absolute;
  top: 100%;
  left: 50%; /* Center below parent */
  transform: translateX(-50%) translateY(5px); /* Adjust position */
  background-color: rgba(91, 46, 152, 0.95); /* Use primary color with opacity */
  border-radius: 5px;
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.4);
  z-index: 101;
  overflow: hidden;
  transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s ease;
  min-width: 180px; /* Minimum width */
}
#main-nav .has-submenu .submenu {
  display: block; /* Luôn là block để tính toán vị trí, nhưng ẩn bằng cách khác */
  visibility: hidden;
  opacity: 0;
  position: absolute;
  top: 100%;
  left: 50%; /* Center below parent */
  transform: translateX(-50%) translateY(10px); /* Start slightly lower */
  background-color: rgba(91, 46, 152, 0.95); /* Use primary color with opacity */
  border-radius: 5px;
  box-shadow: 0 3px 8px rgba(0, 0, 0, 0.4);
  z-index: 101;
  overflow: hidden;
  transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s ease;
  min-width: 180px; /* Minimum width */
  pointer-events: none; /* Ẩn khỏi tương tác chuột khi không active */
}

/* Khi thẻ li.has-submenu có class 'submenu-active' HOẶC khi hover trên desktop */
#main-nav .has-submenu.submenu-active .submenu,
#main-nav .has-submenu:hover .submenu { /* Vẫn giữ hover cho desktop */
  visibility: visible;
  opacity: 1;
  transform: translateX(-50%) translateY(0); /* Final position */
  pointer-events: auto; /* Cho phép tương tác chuột khi active */
}

/* --- CSS CHO DARK MODE (điều chỉnh nếu cần) --- */
body.dark-mode #main-nav .has-submenu .submenu {
  background-color: rgba(20, 20, 20, 0.9); /* Darker submenu */
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.5);
}

/* Các style khác của .submenu a, .submenu li giữ nguyên */
#main-nav .submenu li {
  width: 100%;
}

#main-nav .submenu a {
  padding: 10px 15px;
  display: block;
  font-family: var(--font-family-secondary);
  color: var(--text-color-light);
  transition: background-color 0.2s ease, color 0.2s ease;
  white-space: nowrap;
  font-size: 0.9rem;
}
#main-nav .submenu a i {
    margin-right: 8px;
    font-size: 0.9em;
    width: 1.2em; /* Ensure alignment */
    text-align: center;
}

#main-nav .submenu a:hover {
  background-color: rgba(255, 255, 255, 0.15);
  color: var(--secondary-color);
}
#main-nav .has-submenu:hover .submenu {
  display: block; /* Keep display block for layout */
  visibility: visible;
  opacity: 1;
  transform: translateX(-50%) translateY(0); /* Final position */
}

#main-nav .submenu li {
  width: 100%;
}

#main-nav .submenu a {
  padding: 10px 15px;
  display: block;
  font-family: var(--font-family-secondary);
  color: var(--text-color-light);
  transition: background-color 0.2s ease, color 0.2s ease;
  white-space: nowrap;
  font-size: 0.9rem;
}
#main-nav .submenu a i {
    margin-right: 8px;
    font-size: 0.9em;
    width: 1.2em; /* Ensure alignment */
    text-align: center;
}

#main-nav .submenu a:hover {
  background-color: rgba(255, 255, 255, 0.15);
  color: var(--secondary-color);
}

.right-nav {
  display: flex;
  align-items: center;
  gap: 15px;
}

/* User Info / Van Xu */
#user-info.interactive-van-xu {
  display: inline-flex; /* Use inline-flex */
  align-items: center;
  gap: 10px; /* Consistent gap */
  padding: 6px 12px;
  border-radius: 20px; /* Pill shape */
  background-color: rgba(0, 0, 0, 0.1);
  font-family: var(--font-family-secondary);
  color: var(--text-color-light);
  font-size: 0.9rem; /* Slightly smaller */
  cursor: pointer;
  transition: all 0.3s ease;
  border: 1px solid rgba(255, 255, 255, 0.1);
}
#user-info.interactive-van-xu:hover {
  background-color: rgba(255, 255, 255, 0.1);
  transform: scale(1.03);
  box-shadow: 0 2px 6px rgba(0, 0, 0, 0.3);
  border-color: rgba(255, 255, 255, 0.3);
}
#user-info.interactive-van-xu:active {
  transform: scale(0.99);
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
}
#user-rank, #user-van-xu {
    display: inline-flex; /* Align icon and text */
    align-items: center;
    gap: 5px;
}
#user-info.interactive-van-xu i {
    font-size: 1em; /* Match text size */
    opacity: 0.9;
}
#user-rank i.fa-shield-alt {
    color: var(--secondary-color);
}
#user-van-xu i.fa-coins {
    color: var(--gold-color);
}
#user-van-xu .van-xu-value {
    font-weight: bold;
    color: var(--gold-color);
}
/* Rank Colors */
#user-rank.rank-hoc-gia-to-mo .rank-text { color: #ccc; }
#user-rank.rank-thu-sinh .rank-text { color: #90EE90; } /* LightGreen */
#user-rank.rank-thu-si .rank-text { color: #ADD8E6; } /* LightBlue */
#user-rank.rank-thu-quan .rank-text { color: #E6E6FA; } /* Lavender */
#user-rank.rank-thu-thanh .rank-text { color: gold; }

.rank-up-effect {
  animation: rankUpAnimation 1s ease-in-out;
}
@keyframes rankUpAnimation {
  0%, 100% { transform: scale(1); opacity: 1; }
  50% { transform: scale(1.1); opacity: 0.8; }
}

/* Search Box */
.search-container {
  position: relative;
}
#search-box {
  padding: 8px 35px 8px 15px;
  border-radius: 20px; /* Pill shape */
  border: 1px solid rgba(255, 255, 255, 0.3);
  font-size: 0.9rem;
  background-color: rgba(255, 255, 255, 0.1);
  color: var(--text-color-light);
  transition: all 0.3s ease;
  width: 180px; /* Default width */
}
#search-box:focus {
  outline: none;
  background-color: rgba(255, 255, 255, 0.2);
  box-shadow: 0 0 0 2px var(--primary-color-darker);
  width: 220px; /* Expand on focus */
}
#search-box:hover {
  background-color: rgba(255, 255, 255, 0.15);
  border-color: rgba(255, 255, 255, 0.5);
}
#search-box::placeholder {
    color: rgba(255, 255, 255, 0.7);
}
#search-button {
  position: absolute;
  right: 10px;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  cursor: pointer;
  font-size: 1em;
  color: rgba(255, 255, 255, 0.8);
  opacity: 0.8;
  transition: opacity 0.3s ease, color 0.3s ease;
}
#search-button:hover {
  opacity: 1;
  color: #fff;
}
#search-suggestions {
  position: absolute;
  top: calc(100% + 5px); /* Position below search */
  left: 0;
  right: 0;
  background-color: var(--secondary-color);
  border-radius: 5px;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.2);
  display: none; /* Hidden by default */
  z-index: 102;
  padding: 0.5rem 0;
  list-style: none;
  margin: 0;
  max-height: 200px; /* Limit height */
  overflow-y: auto;
}
#search-suggestions li {
  padding: 0.6rem 1rem;
  cursor: pointer;
  transition: background-color 0.2s ease;
  color: var(--text-color-dark);
  text-align: left;
  font-size: 0.9rem;
}
#search-suggestions li:hover {
  background-color: rgba(0, 0, 0, 0.1);
}
#search-suggestions .no-results {
  padding: 0.6rem 1rem;
  color: #777;
  font-style: italic;
  cursor: default;
}

/* Theme Toggle */
.theme-toggle button {
  background: none;
  border: none;
  color: var(--text-color-light);
  font-size: 1.2em;
  cursor: pointer;
  transition: color 0.3s ease, transform 0.3s ease, opacity 0.3s ease;
  padding: 8px;
  border-radius: 50%;
  opacity: 0.9;
  display: flex; /* Center icon */
  align-items: center;
  justify-content: center;
}
.theme-toggle button:hover {
  color: var(--secondary-color);
  transform: scale(1.1) rotate(15deg);
  opacity: 1;
}
.theme-toggle button i {
  transition: transform 0.5s ease-in-out;
}

/* Login/Logout Buttons */
.login-menu {
  position: relative;
}
#login-button, #logout-button {
  background: none;
  border: 1px solid var(--secondary-color);
  color: var(--text-color-light);
  font-size: 0.9rem;
  cursor: pointer;
  padding: 7px 15px; /* Adjusted padding */
  border-radius: 20px;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  gap: 6px;
}
#login-button:hover, #logout-button:hover {
  background-color: var(--secondary-color);
  color: var(--primary-color);
  border-color: var(--secondary-color);
  transform: translateY(-2px);
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}
#user-dropdown {
  display: none; /* Handled by JS */
}
#user-dropdown button {
  /* Logout inherits styles, no specific dropdown style needed yet */
}

/* --- Main Content Area --- */
.main-content {
  padding-top: var(--nav-height-desktop); /* Space below fixed nav */
  position: relative; /* Needed for loading overlay */
}

/* Loading Overlay */
.loading-overlay {
  position: fixed; /* Cover viewport */
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.7);
  display: flex;
  justify-content: center;
  align-items: center;
  z-index: 999; /* High z-index */
  opacity: 0;
  transition: opacity 0.3s ease;
  pointer-events: none;
}
.loading-overlay.active {
  opacity: 1;
  pointer-events: auto;
}
.loading-spinner {
  border: 4px solid #f3f3f3;
  border-top: 4px solid var(--primary-color);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  animation: spin 1s linear infinite;
}
@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

/* Content Sections */
.content-section {
  display: none; /* Hidden by default */
  opacity: 0;
  transform: translateY(20px);
  transition: opacity 0.4s ease, transform 0.4s ease;
  margin-bottom: 2.5rem; /* Spacing between sections */
  padding: 0 10px; /* Add some horizontal padding */
}
.content-section.active {
  display: block;
  opacity: 1;
  transform: translateY(0);
}

/* --- Trang Chủ Specific --- */
#trang-chu .social-icons .icon {
  /* == KÍCH THƯỚC ICON TRANG CHỦ (DESKTOP) == */
  width: 60px;     /* << THAY ĐỔI chiều rộng vòng tròn DESKTOP */
  height: 60px;    /* << THAY ĐỔI chiều cao vòng tròn DESKTOP */
  font-size: 30px;
}

/* Social Icons (shared) */
.social-icons {
  display: flex;
  justify-content: center; /* Center on page */
  gap: 20px; /* Spacing */
  margin-bottom: 2rem; /* Space below icons */
  margin-top: 1rem; /* Space above icons */
}
.icon {
  width: 50px; /* Slightly smaller */
  height: 50px;
  border-radius: 50%;
  transition: all 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  display: flex;
  justify-content: center;
  align-items: center;
  text-decoration: none;
  font-size: 24px; /* Adjusted size */
  color: white;
  box-shadow: 0 8px 15px rgba(0,0,0,0.15), 0 4px 4px rgba(0,0,0,0.1);
}
.icon:hover {
  transform: translateY(-4px) scale(1.05);
  box-shadow: 0 12px 25px rgba(0,0,0,0.2), 0 8px 8px rgba(0,0,0,0.15);
}
.icon:active {
  transform: translateY(-1px) scale(0.98);
  box-shadow: 0 4px 8px rgba(0,0,0,0.15), 0 2px 2px rgba(0,0,0,0.1);
}
.icon-facebook { background: #1877f2; }
.icon-tiktok { background: #000; }
.icon-youtube { background: #ff0000; }
.icon-facebook:hover { background: #166fe5; }
.icon-tiktok:hover { background: #333; }
.icon-youtube:hover { background: #cc0000; }

/* New Books Carousel */
#new-books {
  margin-bottom: 2.5rem;
}
.new-books-carousel {
  position: relative;
  overflow: hidden;
  width: 100%;
  max-width: 800px; /* Adjust max width as needed */
  margin: 1rem auto; /* Centering */
  border-radius: 8px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.2);
}
.new-books-inner {
  display: flex;
  transition: transform 0.5s ease;
}
.new-book-item {
  flex: 0 0 100%; /* Each item takes full width */
  position: relative;
  aspect-ratio: 16 / 7; /* Adjust aspect ratio for desired height */
  cursor: pointer;
  overflow: hidden; /* Clip image */
}
.new-book-item img {
  width: 100%;
  height: 100%;
  object-fit: cover; /* Cover the area */
  transition: transform 0.4s ease;
}
.new-book-item:hover img {
    transform: scale(1.05); /* Slight zoom on hover */
}
.new-book-overlay {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  background: linear-gradient(to top, rgba(0, 0, 0, 0.8), rgba(0, 0, 0, 0)); /* Gradient overlay */
  color: white;
  padding: 1.5rem 1rem 1rem; /* More padding */
  text-shadow: 1px 1px 3px rgba(0,0,0,0.6);
}
.new-book-overlay h3 {
  margin: 0;
  font-size: 1.6em;
  font-family: var(--font-family-primary);
  color: #fff; /* Ensure white */
}
.new-book-overlay p {
  margin: 0.3rem 0 0;
  font-size: 0.9em;
  font-family: var(--font-family-secondary);
  color: rgba(255, 255, 255, 0.9);
}

/* Featured Books Carousel */
#featured-books {
  margin-bottom: 2.5rem;
}
.carousel {
  display: flex;
  overflow-x: auto;
  overflow-y: hidden; /* Hide vertical scrollbar */
  gap: 1rem; /* Space between items */
  padding: 1rem 0.5rem 1.5rem; /* Top, sides, bottom padding */
  scroll-behavior: smooth;
  scroll-snap-type: x mandatory; /* Snap scrolling */
  -webkit-overflow-scrolling: touch; /* Smooth scrolling on iOS */
}
/* Add subtle scrollbar styling */
.carousel::-webkit-scrollbar {
  height: 8px;
}
.carousel::-webkit-scrollbar-track {
  background: rgba(0, 0, 0, 0.1);
  border-radius: 4px;
}
.carousel::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.3);
  border-radius: 4px;
}
body.dark-mode .carousel::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.2);
}
.carousel-item {
  flex: 0 0 220px; /* Fixed width for carousel items */
  scroll-snap-align: start; /* Snap alignment */
  border-radius: 8px;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.1);
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  background-color: var(--background-light); /* Light bg for items */
  color: var(--text-color-dark); /* Dark text */
  overflow: hidden; /* Ensure content fits */
  display: flex; /* Use flex for structure */
  flex-direction: column;
}
.carousel-item:hover {
  transform: translateY(-5px);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
}

/* --- Book Display (All Books & Categories) --- */
.book-container {
  display: grid; /* Use grid for responsive layout */
  grid-template-columns: repeat(auto-fill, minmax(200px, 1fr)); /* Responsive columns */
  gap: 1.5rem; /* Gap between books */
  margin-bottom: 2rem;
}

.book, .carousel-item { /* Shared styles for book cards */
  background-color: var(--background-light);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  box-shadow: 0 2px 5px var(--box-shadow-color);
  text-align: center;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  cursor: pointer;
  display: flex;
  flex-direction: column;
  overflow: hidden; /* Prevent content overflow */
  color: var(--text-color-dark);
  padding: 0.8rem; /* Internal padding */
  justify-content: space-between; /* Distribute space */
  min-height: 420px; /* Minimum height for consistency */
}
.book:hover {
  transform: translateY(-5px);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.15);
}

.book-image {
  width: 100%;
  aspect-ratio: 2 / 3; /* Maintain aspect ratio */
  object-fit: cover;
  border-radius: 4px;
  margin-bottom: 0.8rem;
}

.book-title-container {
  min-height: 3.2em; /* Allow space for two lines */
  margin-bottom: 0.5rem;
  display: flex; /* Center text vertically */
  align-items: center;
  justify-content: center;
}
.book h3 { /* Includes carousel item h3 */
  font-family: var(--font-family-primary);
  font-size: 1.1em;
  line-height: 1.3;
  overflow: hidden;
  text-overflow: ellipsis;
  display: -webkit-box;
  -webkit-line-clamp: 2; /* Limit to 2 lines */
  -webkit-box-orient: vertical;
  margin: 0; /* Remove default margin */
  color: var(--text-color-dark); /* Ensure dark text */
  text-shadow: none; /* No shadow on light bg */
}

.book-publication-date {
  font-size: 0.8em;
  color: #666; /* Grey color for date */
  font-family: var(--font-family-secondary);
  margin-bottom: 0.5rem;
}

.ratings {
  display: flex;
  justify-content: center;
  align-items: center;
  margin-bottom: 0.8rem;
  gap: 2px;
}
.ratings .star {
  color: var(--star-color-inactive);
  font-size: 1em; /* Adjust size */
  cursor: pointer;
  transition: color 0.2s ease, transform 0.2s ease;
}
.ratings .star:hover {
    transform: scale(1.2);
}
.ratings .star.active,
.ratings .star.half { /* Style half stars same as active */
  color: var(--star-color-active);
}
.ratings .star.half i::before { /* Use Font Awesome's half-star icon */
    content: "\f5c0"; /* Unicode for fa-star-half-alt */
    font-family: "Font Awesome 5 Free";
    font-weight: 900;
}

.button-group {
  display: flex;
  flex-direction: column;
  gap: 0.5rem; /* Space between rows */
  margin-top: auto; /* Push buttons to bottom */
}
.button-row {
  display: flex;
  justify-content: space-around; /* Space out buttons */
  align-items: center;
  gap: 0.5rem;
}

/* Specific Button Styles within Book Cards */
.book .purchase-button,
.book .read-button {
  flex-grow: 1; /* Allow buttons to grow */
  padding: 0.5rem 0.8rem;
  border: none;
  border-radius: 5px;
  font-size: 0.85em;
  font-weight: bold;
  transition: all 0.2s ease;
  box-shadow: 0 1px 2px rgba(0,0,0,0.1);
}
.book .purchase-button {
  background-color: var(--primary-color);
  color: white;
}
.book .read-button {
  background-color: #9b59b6; /* Different color for read */
  color: white;
}
.book .purchase-button:hover {
  background-color: var(--primary-color-darker);
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
  transform: translateY(-1px);
}
.book .read-button:hover {
  background-color: #8e44ad;
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
  transform: translateY(-1px);
}

.book .add-to-cart-button,
.book .favorite-button {
  background: none;
  border: none;
  font-size: 1.3em; /* Icon size */
  color: #aaa; /* Default icon color */
  cursor: pointer;
  transition: color 0.2s ease, transform 0.2s ease;
  padding: 5px; /* Add padding for easier clicking */
  line-height: 1; /* Prevent extra space */
  display: flex;
  align-items: center;
  justify-content: center;
}
.book .add-to-cart-button:hover {
  color: var(--primary-color); /* Color on hover */
  transform: scale(1.1);
}
.book .favorite-button:hover {
  color: #e74c3c; /* Red hover for favorite */
  transform: scale(1.1);
}
.book .favorite-button.active {
  color: #e74c3c; /* Red when active */
}
.book .favorite-button.active:hover {
  color: #c0392b; /* Darker red */
}


/* --- Category Section --- */
#the-loai h2 { /* Category Title */
    margin-bottom: 1rem;
}
.category-section {
  display: none; /* Hidden by default */
  margin-bottom: 2.5rem;
}
.category-section.active {
  display: block;
}
.category-section h3 { /* Sub-category Titles */
    font-size: 1.5rem;
    text-align: center;
    margin-bottom: 1.5rem;
    color: var(--primary-color); /* Use primary color */
    text-shadow: 1px 1px 1px rgba(0,0,0,0.2);
}
body.dark-mode .category-section h3 {
    color: var(--gold-color); /* Gold in dark mode */
    text-shadow: 1px 1px 2px rgba(0,0,0,0.5);
}

/* --- Pagination --- */
.pagination {
  display: flex;
  justify-content: center;
  align-items: center;
  margin-top: 2rem; /* Space above pagination */
  flex-wrap: wrap; /* Allow wrapping */
  gap: 0.5rem; /* Space between buttons */
}
.pagination button {
  padding: 0.5rem 0.9rem;
  margin: 0; /* Remove margin, use gap */
  border: 1px solid var(--border-color);
  border-radius: 4px;
  background-color: var(--secondary-color);
  color: var(--text-color-dark);
  cursor: pointer;
  transition: all 0.2s ease;
  font-size: 0.9rem;
}
.pagination button:hover:not(:disabled) {
  background-color: var(--primary-color);
  color: var(--text-color-light);
  border-color: var(--primary-color);
  transform: translateY(-1px);
}
.pagination button:disabled {
  background-color: #e0e0e0;
  color: #999;
  cursor: default;
  border-color: #ccc;
}
.pagination button.active { /* Style for current page (if needed, JS adds class) */
  background-color: var(--primary-color);
  color: var(--text-color-light);
  font-weight: bold;
  border-color: var(--primary-color-darker);
  cursor: default;
}

/* --- Auth Forms (Login/Register) --- */
.auth-section {
  display: none;
  justify-content: center;
  align-items: center;
  min-height: calc(100vh - var(--nav-height-desktop)); /* Fill space below nav */
  padding: 2rem 1rem;
}
.auth-section.active {
  display: flex;
}

.form-container {
  background: var(--login-form-bg);
  padding: 2.5rem;
  border-radius: 12px;
  text-align: center;
  box-shadow: var(--login-form-shadow);
  width: 100%; /* Full width on mobile, max on desktop */
  max-width: 400px;
  position: relative;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
  color: var(--text-color-light);
}
.form-container:hover {
  transform: translateY(-5px);
  box-shadow: var(--login-form-hover-shadow);
}

.form-title {
  font-size: 1.8em;
  margin-bottom: 0.8rem;
  font-weight: 600;
  color: #fff;
}
.form-subtitle {
  font-size: 1em;
  margin-bottom: 2rem;
  color: rgba(255, 255, 255, 0.8);
}
.input-group {
  position: relative;
  margin-bottom: 1.8rem;
}
.form-input {
  width: 100%;
  padding: 1rem; /* Slightly more padding */
  border: none;
  border-radius: 6px;
  background-color: var(--login-input-bg);
  color: var(--text-color-light);
  font-size: 1em;
  outline: none;
  transition: all 0.3s ease;
  border: 1px solid transparent; /* Placeholder for error border */
}
.form-input:focus {
  background-color: var(--login-input-focus-bg);
  box-shadow: 0 0 0 2px rgba(98, 0, 238, 0.4);
  border-color: rgba(98, 0, 238, 0.4);
}
.form-input::placeholder {
    color: rgba(255, 255, 255, 0.6);
}
.input-label { /* Floating label effect */
  position: absolute;
  left: 1rem;
  top: 1rem;
  color: rgba(255, 255, 255, 0.7);
  pointer-events: none;
  transition: all 0.2s ease;
  background-color: var(--login-form-bg); /* Match background */
  padding: 0 0.3rem; /* Padding for background */
}
.form-input:focus + .input-label,
.form-input:not(:placeholder-shown) + .input-label {
  top: -0.6rem; /* Move label up */
  font-size: 0.8em;
  color: var(--text-color-light);
}
.error-message {
  display: none;
  color: var(--error-color);
  font-size: 0.85em;
  margin-top: 0.4rem;
  text-align: left;
}
.input-group.error .form-input {
  border: 1px solid var(--error-color);
}
.input-group.error .error-message {
  display: block;
}

.password-input-group {
  position: relative;
}
.password-toggle-button {
  position: absolute;
  right: 0.8rem;
  top: 50%;
  transform: translateY(-50%);
  background: none;
  border: none;
  color: rgba(255, 255, 255, 0.7);
  font-size: 1.1em;
  cursor: pointer;
  padding: 0;
  transition: color 0.3s ease;
}
.password-toggle-button:hover {
  color: var(--text-color-light);
}

.remember-me-container {
  display: flex;
  align-items: center;
  justify-content: flex-start; /* Align left */
  margin-bottom: 1rem;
  margin-top: -0.8rem; /* Pull up slightly */
}
.remember-me-container input[type="checkbox"] {
  margin-right: 0.5rem;
  width: 16px;
  height: 16px;
}
.remember-me-container label {
  font-size: 0.9em;
  color: rgba(255, 255, 255, 0.8);
  user-select: none;
}

.interactive-button, .sign-in-button { /* Shared button style */
  display: block; /* Full width */
  width: 100%;
  padding: 0.9rem 1.5rem;
  border: none;
  border-radius: 6px;
  background-color: var(--login-button-bg);
  color: var(--text-color-light);
  font-size: 1.05em;
  font-weight: bold;
  cursor: pointer;
  transition: all 0.3s ease;
  outline: none;
  margin-top: 1rem; /* Space above button */
}
.interactive-button:hover, .sign-in-button:hover {
  background-color: var(--login-button-hover-bg);
  transform: translateY(-2px);
  box-shadow: 0 4px 10px rgba(98, 0, 238, 0.3);
}
.interactive-button:active, .sign-in-button:active {
  transform: translateY(0);
  box-shadow: 0 1px 3px rgba(98, 0, 238, 0.2);
}

.forgot-password-container {
  margin-top: 1rem;
  text-align: right; /* Align right */
}
.forgot-password-link {
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.9em;
  text-decoration: none;
  transition: color 0.3s ease;
}
.forgot-password-link:hover {
  color: var(--text-color-light);
  text-decoration: underline;
}

.or-continue {
  margin: 1.5rem 0;
  color: rgba(255, 255, 255, 0.7);
  font-size: 0.9em;
  text-align: center;
  position: relative;
  text-transform: uppercase;
}
.or-continue::before, .or-continue::after {
    content: '';
    position: absolute;
    top: 50%;
    width: 35%; /* Adjust width of lines */
    height: 1px;
    background-color: rgba(255, 255, 255, 0.3);
}
.or-continue::before { left: 0; }
.or-continue::after { right: 0; }

.social-buttons {
  display: flex;
  justify-content: center;
  gap: 1rem;
  margin-bottom: 1.5rem;
}
.social-button {
  background-color: rgba(255, 255, 255, 0.1);
  color: var(--text-color-light);
  width: 45px; /* Slightly larger */
  height: 45px;
  border-radius: 50%;
  display: flex;
  justify-content: center;
  align-items: center;
  font-size: 1.2em;
  border: none;
  cursor: pointer;
  transition: all 0.3s ease;
}
.social-button:hover {
  background-color: rgba(255, 255, 255, 0.2);
  transform: scale(1.1);
}

.form-footer {
  font-size: 0.95em;
  color: rgba(255, 255, 255, 0.8);
  text-align: center;
  margin-top: 1.5rem;
}
.sign-up-link {
  color: var(--text-color-light);
  text-decoration: none;
  font-weight: bold;
  border-bottom: 1px solid transparent;
  transition: border-color 0.3s ease, color 0.3s ease;
}
.sign-up-link:hover {
  color: var(--secondary-color);
  border-color: var(--secondary-color);
}

/* --- Yêu Thích Section --- */
#yeu-thich-container {
    /* Uses .book-container styles */
}
#empty-favorites {
  display: none; /* Hidden by default, shown by JS */
  text-align: center;
  margin-top: 2rem;
  font-style: italic;
  color: rgba(255, 255, 255, 0.8);
  font-size: 1.1rem;
}

/* --- Lịch Sử Mua Hàng Section --- */
#lich-su-mua-hang table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 1.5rem;
  background-color: rgba(0, 0, 0, 0.1); /* Subtle background */
  border-radius: 8px;
  overflow: hidden; /* Clip rounded corners */
  box-shadow: 0 2px 5px rgba(0,0,0,0.2);
}
#lich-su-mua-hang th,
#lich-su-mua-hang td {
  padding: 0.8rem 1rem;
  text-align: left;
  border-bottom: 1px solid rgba(255, 255, 255, 0.15);
}
#lich-su-mua-hang th {
  background-color: rgba(255, 255, 255, 0.1);
  font-weight: bold;
  font-family: var(--font-family-secondary);
  font-size: 0.95rem;
  color: rgba(255, 255, 255, 0.9);
}
#lich-su-mua-hang td {
    font-size: 0.9rem;
    color: rgba(255, 255, 255, 0.85);
}
#lich-su-mua-hang tr:last-child td {
    border-bottom: none;
}
#lich-su-mua-hang tr:hover {
    background-color: rgba(255, 255, 255, 0.05);
}

#empty-purchase-history {
  display: none; /* Hidden by default, shown by JS */
  text-align: center;
  margin-top: 2rem;
  font-style: italic;
  color: rgba(255, 255, 255, 0.8);
  font-size: 1.1rem;
}

/* --- Liên Hệ Section --- */
#lien-he {
  text-align: center;
  padding: 1rem;
  background-color: rgba(0, 0, 0, 0.1);
  border-radius: 8px;
}
#lien-he p {
  margin-bottom: 0.8rem;
  font-size: 1.1rem;
  line-height: 1.6;
  color: rgba(255, 255, 255, 0.9);
}
#lien-he a {
  color: var(--gold-color);
  font-weight: bold;
}
#lien-he a:hover {
  color: #ffeb3b; /* Lighter gold */
}

/* --- Book Details Section --- */
#book-details {
  padding: 2rem; /* Add some vertical padding */
}
.book-details-content {
  display: flex;
  gap: 2rem; /* Increased gap */
  background-color: var(--background-light);
  padding: 2rem; /* More padding */
  border-radius: 10px;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.15);
  color: var(--text-color-dark); /* Dark text on light bg */
  position: relative; /* For close button positioning */
}
#close-book-details-button {
  position: absolute;
  top: 0.8rem;
  right: 0.8rem;
  background: none;
  border: none;
  font-size: 1.8rem; /* Larger icon */
  color: #aaa;
  cursor: pointer;
  opacity: 0.8;
  transition: all 0.2s ease;
  padding: 5px; /* Easier click target */
  line-height: 1;
}
#close-book-details-button:hover {
  opacity: 1;
  color: #555;
  transform: scale(1.1);
}

.book-cover {
  flex: 0 0 250px; /* Fixed width for cover */
  text-align: center;
}
.book-cover img {
  max-width: 100%;
  border-radius: 6px;
  box-shadow: 0 4px 8px rgba(0,0,0,0.2);
  margin-bottom: 1rem; /* Space below image */
}
#book-details-rating {
    justify-content: center; /* Center stars */
    margin-bottom: 0.5rem;
}
#book-details-publication-date {
  font-size: 0.9em;
  color: #555;
}

.book-info {
  flex: 1; /* Take remaining space */
  display: flex;
  flex-direction: column;
}
.book-info h2 {
  font-size: 2em; /* Larger title */
  margin-bottom: 0.5rem;
  color: var(--primary-color);
  text-shadow: none;
}
.book-info p {
  margin-bottom: 0.8rem;
  line-height: 1.6;
  font-size: 1rem;
  color: #444; /* Darker paragraph text */
}
.book-info p .info-value { /* Style for the actual data */
        color: #333;
    font-weight: 500;
}
#book-details-description {
    margin-top: 1rem; /* Space above description */
}
#book-details-description .info-value {
    font-family: 'Roboto', sans-serif;
    display: block; /* Make description value block */
    margin-top: 0.3rem;
    font-style: italic;
    color: #555;
}

.book-actions {
  display: flex;
  flex-wrap: wrap; /* Allow wrapping */
  gap: 0.8rem; /* Space between actions */
  margin-top: 1rem; /* Space above actions */
  margin-bottom: 1.5rem;
  align-items: center; /* Align items vertically */
}
/* Shared button styles for details page */
.book-actions button {
  padding: 0.7rem 1.2rem;
  border-radius: 6px;
  font-size: 0.95rem;
  font-weight: bold;
  border: none;
  transition: all 0.2s ease;
  display: inline-flex; /* Align icon and text */
  align-items: center;
  gap: 8px;
  box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}
.book-actions button:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 8px rgba(0,0,0,0.15);
}
.book-actions button:active {
    transform: translateY(0);
    box-shadow: 0 1px 2px rgba(0,0,0,0.1);
}
.book-actions .primary-button { /* Thỉnh thư */
  background-color: var(--primary-color);
  color: white;
}
.book-actions .secondary-button { /* Đọc thử */
  background-color: #9b59b6;
  color: white;
}
.book-actions .tertiary-button { /* Add to Cart, Favorite */
  background: none;
  color: #888; /* Default icon color */
  font-size: 1.6em; /* Larger icons */
  padding: 5px; /* Click area */
  box-shadow: none;
}
.book-actions .tertiary-button:hover {
    transform: scale(1.1);
    box-shadow: none;
}
.book-actions .add-to-cart:hover {
    color: var(--primary-color);
}
.book-actions .favorite-button span {
    display: none; /* Hide "Yêu thích" text, rely on icon */
}
.book-actions .favorite-button:hover {
    color: #e74c3c;
}
.book-actions .favorite-button.active {
  color: #e74c3c;
}
.book-actions .favorite-button.active:hover {
  color: #c0392b;
}
.book-actions .favorite-button.active i { /* Pulse animation */
    animation: pulse 0.6s ease;
}
@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.2); }
}

.comments-section {
  margin-top: 1.5rem;
  border-top: 1px solid #eee; /* Separator */
  padding-top: 1.5rem;
}
.comments-section h3 {
  font-size: 1.3em;
  margin-bottom: 1rem;
  color: #555;
  text-shadow: none;
}
#book-details-comments {
  margin-bottom: 1rem;
  max-height: 200px; /* Limit comment height */
  overflow-y: auto;
  padding-right: 10px; /* Space for scrollbar */
}
#book-details-comments p { /* Individual comment style */
  background-color: rgba(255, 255, 255, 0.05);
  padding: 0.8rem;
  margin-bottom: 0.8rem;
  border-radius: 4px;
  border: 1px solid #eee;
  font-size: 0.95rem;
  line-height: 1.5;
}
#book-details-comment-box {
  width: 100%;
  padding: 0.8rem;
  margin-bottom: 0.8rem;
  border: 1px solid var(--border-color);
  border-radius: 5px;
  resize: vertical;
  min-height: 80px;
  font-size: 1rem;
  color: #333;
  background-color: #fff;
}
#book-details-comment-submit {
  background-color: var(--primary-color);
  color: white;
  padding: 0.6rem 1.2rem;
  border-radius: 5px;
  font-size: 0.95rem;
  font-weight: bold;
  border: none;
  transition: all 0.2s ease;
}
#book-details-comment-submit:hover {
  background-color: var(--primary-color-darker);
  box-shadow: 0 2px 4px rgba(0,0,0,0.2);
}

/* --- Footer --- */
.site-footer {
  border-radius: 1rem 1rem 0 0; /* Rounded top corners */
  background: linear-gradient(145deg, rgba(17, 82, 106, 0.9), rgba(91, 46, 152, 0.9));
  color: #eee;
  padding: 2rem 1rem 1.5rem; /* Increased top padding, consistent side/bottom */
  font-family: var(--font-family-secondary);
  margin-top: 1rem; /* Space above footer */
  box-shadow: 0 -4px 10px rgba(0, 0, 0, 0.2); /* Add a subtle top shadow */
}

.footer-container {
  display: flex;
  justify-content: space-between; /* Keep space between */
  max-width: 1200px;
  margin: 0 auto;
  flex-wrap: wrap; /* Allow wrapping on smaller desktops */
  gap: 2rem 1.5rem; /* Increased row and column gap */
}

.footer-section {
  flex: 1; /* Allow sections to grow/shrink */
  min-width: 220px; /* Minimum width before wrapping */
  padding: 0 1rem; /* Add horizontal padding within sections */
  display: flex; /* Use flex for vertical alignment */
  flex-direction: column; /* Stack content vertically */
}

.footer-title {
  font-size: 1.15rem; /* Slightly larger title */
  margin-bottom: 1.2rem; /* More space below title */
  color: var(--gold-color);
  font-weight: bold;
  text-transform: uppercase;
  letter-spacing: 1px;
  display: flex; /* Align icon and text */
  align-items: center;
  gap: 0.6rem; /* Space between icon and text */
  /* text-align: center; /* Optional: Center titles */
}

.footer-title i { /* Style title icons */
  font-size: 1.1em;
  opacity: 0.9;
}

.footer-section p {
  font-size: 0.9rem;
  line-height: 1.6;
  color: rgba(255, 255, 255, 0.85); /* Slightly brighter text */
  margin-bottom: 0.8rem;
  overflow-wrap: break-word; /* Ensure long text wraps */
}

.footer-section ul {
  padding: 0;
  margin: 0;
  list-style: none; /* Ensure list style is none */
}

.footer-section ul li {
  margin-bottom: 0.7rem; /* More space between list items */
}

.footer-section ul li a {
  color: rgba(255, 255, 255, 0.85);
  text-decoration: none;
  font-size: 0.95rem; /* Slightly larger links */
  transition: color 0.2s ease;
  display: inline-flex;
  align-items: center;
  gap: 8px;
}

.footer-section ul li a:hover {
  color: #fff;
}

.footer-section ul li a i {
  opacity: 0.8;
  width: 1.2em; /* Help align icons */
  text-align: center;
}

/* Footer Social Icons */
.footer-section .social-icons {
  justify-content: flex-start; /* Align left by default */
  margin-top: 0.5rem;
  margin-bottom: 0;
  gap: 10px; /* Adjust gap */
}
/* Center social icons if section is centered (optional) */
/* .footer-section.center-align .social-icons {
    justify-content: center;
} */

.footer-section .social-icons .icon {
  width: 58px; /* Slightly larger icons */
  height: 58px;
  font-size: 35px;
  box-shadow: 0 4px 8px rgba(0,0,0,0.15); /* Adjust shadow */
}
.footer-section .social-icons .icon:hover {
    transform: translateY(-3px) scale(1.05);
    box-shadow: 0 6px 12px rgba(0,0,0,0.2);
}

.xem-them-link { /* "Xem thêm" link */
  color: var(--gold-color);
  font-weight: bold;
  cursor: pointer;
  border-bottom: 1px solid transparent; /* Add underline on hover */
  transition: color 0.2s ease, border-color 0.2s ease;
}

.xem-them-link:hover {
  color: #ffeb3b;
  border-color: #ffeb3b;
}

/* Newsletter Section Specifics */
.newsletter-text {
  font-size: 0.9rem;
  margin-bottom: 0.8rem;
  color: rgba(255, 255, 255, 0.85);
}

#newsletter-form {
  display: flex;
  gap: 8px;
  margin-top: 0.5rem;
  align-items: center; /* Align input and button vertically */
  flex-wrap: wrap; /* Allow wrap on smaller widths */
}

#newsletter-form input {
  flex: 1 1 180px; /* Allow input to grow but have a base size */
  padding: 0.7rem;
  border: 1px solid rgba(255, 255, 255, 0.3);
  border-radius: 5px;
  font-size: 0.9rem;
  background-color: rgba(255, 255, 255, 0.1);
  color: #fff;
  min-width: 150px; /* Prevent input becoming too small */
}

#newsletter-form input::placeholder {
  color: rgba(255, 255, 255, 0.6);
}

#newsletter-form button {
  padding: 0.4rem 1rem;
  background-color: var(--primary-color);
  color: white;
  border: none;
  cursor: pointer;
  border-radius: 5px;
  display: inline-flex;
  align-items: center;
  gap: 6px; /* Increased gap */
  font-size: 0.9rem;
  font-weight: bold;
  transition: background-color 0.2s ease, transform 0.2s ease;
  flex-shrink: 0; /* Prevent button from shrinking */
}

#newsletter-form button:hover {
  background-color: var(--primary-color-darker);
  transform: scale(1.03); /* Slight scale effect */
}
#newsletter-form button i {
    font-size: 0.9em;
}


/* Footer Bottom */
.footer-bottom {
  text-align: center;
  border-top: 1px solid rgba(255, 255, 255, 0.2);
  padding-top: 1.5rem;
  margin-top: 1rem; /* More space above bottom */
  font-size: 0.85rem;
  color: rgba(255, 255, 255, 0.75); /* Slightly brighter */
  width: 100%; /* Ensure it spans */
}

.footer-bottom p { /* Target the copyright paragraph */
    margin-bottom: 0.8rem; /* Space below copyright */
}

.footer-bottom a {
  color: var(--gold-color);
  text-decoration: none;
  margin: 0 10px;
  display: inline-flex;
  align-items: center;
  gap: 5px;
  transition: color 0.2s ease;
  border-bottom: 1px solid transparent;
  padding-bottom: 2px;
}

.footer-bottom a:hover {
  color: #ffeb3b;
  border-color: #ffeb3b;
}
.footer-bottom i {
    opacity: 0.8;
}

/* --- Popups (Payment, About, Newsletter Notification) --- */
.overlay { /* Shared overlay style */
  display: none; /* Hidden by default */
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-color: rgba(0, 0, 0, 0.7); /* Darker overlay */
  z-index: 1002;
  justify-content: center;
  align-items: center;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.3s ease;
  padding: 1rem; /* Padding for content */
  overflow-y: auto; /* Allow scrolling if content overflows */
}
.overlay.active {
  display: flex;
  opacity: 1;
  pointer-events: auto;
}

/* Base Popup Style */
.overlay > .form-container.glassmorphism {
  width: 90%;
  max-width: 500px; /* Default max width */
  padding: 2rem;
  margin: auto; /* Center vertically */
  border-radius: 10px;
  text-align: center;
  box-shadow: 0 5px 20px rgba(0, 0, 0, 0.3);
  position: relative; /* For close icon */
  transform: scale(0.95);
  opacity: 0;
  transition: transform 0.3s ease, opacity 0.3s ease;
  background: var(--popup-bg-light); /* Default light background */
  color: var(--text-color-dark);
}
.overlay.active > .form-container.glassmorphism {
  transform: scale(1);
  opacity: 1;
}

/* Popup Close Icons */
.overlay #payment-popup-close-icon,
.overlay #close-ve-chung-toi-popup,
.overlay #close-newsletter-popup-icon {
  position: absolute;
  top: 0.8rem;
  right: 0.8rem;
  background: none;
  border: none;
  font-size: 1.6rem;
  color: #aaa;
  cursor: pointer;
  opacity: 0.8;
  transition: all 0.2s ease;
  padding: 5px;
  line-height: 1;
}
.overlay #payment-popup-close-icon:hover,
.overlay #close-ve-chung-toi-popup:hover,
.overlay #close-newsletter-popup-icon:hover {
  opacity: 1;
  color: #555;
  transform: scale(1.1);
}

/* Payment Popup Specifics */
#payment-popup {
    max-width: 450px; /* Smaller max-width */
}
#payment-popup h2 {
  font-size: 1.5em;
  margin-bottom: 1rem;
  color: var(--primary-color);
}
#payment-popup .account-info {
  margin-bottom: 1.5rem;
}
#payment-popup .account-info p {
  margin-bottom: 0.5rem;
  font-size: 1.1rem;
  color: #444;
}
#payment-popup .account-info .account-number {
  font-weight: bold;
  font-size: 1.4rem;
  color: var(--primary-color-darker);
  user-select: all; /* Allow easy selection */
}
#payment-popup .qr-code {
    margin: 1rem auto 1.5rem;
    max-width: 200px; /* Limit QR code size */
}
#payment-popup .qr-code img {
  max-width: 100%;
  height: auto;
  border: 1px solid var(--border-color);
  border-radius: 5px;
}
#payment-popup .payment-instructions {
  margin-bottom: 1.5rem;
  text-align: left;
}
#payment-popup .payment-instructions p {
  font-size: 1rem;
  margin-bottom: 0.5rem;
  color: #555;
}
#payment-content-template {
  background-color: #eee;
  color: #333;
  padding: 0.8rem;
  border-radius: 5px;
  display: block;
  margin-bottom: 0.8rem;
  font-family: monospace;
  overflow-wrap: break-word;
  border: 1px solid #ddd;
  user-select: all;
}
#reader-gmail {
  width: 100%;
  padding: 0.8rem;
  border: 1px solid var(--border-color);
  border-radius: 5px;
  background-color: #fff;
  color: #333;
  font-size: 1rem;
  margin-bottom: 1rem;
}
#reader-gmail::placeholder {
    color: #999;
}
#payment-popup .payment-actions {
    display: flex;
    justify-content: center;
    gap: 1rem;
    margin-top: 1rem;
}
#copy-payment-content-button, #close-payment-popup {
  padding: 0.8rem 1.5rem;
  border-radius: 6px;
  font-size: 1rem;
  font-weight: bold;
}
#copy-payment-content-button {
    background-color: var(--primary-color);
    color: white;
}
#copy-payment-content-button:hover {
    background-color: var(--primary-color-darker);
}
#close-payment-popup {
    background-color: #aaa;
    color: #fff;
}
#close-payment-popup:hover {
    background-color: #888;
}
#payment-popup .note {
    font-size: 0.9rem;
    color: #777;
    margin-top: 1.5rem;
}

/* "Về Chúng Tôi" Popup Specifics */
#ve-chung-toi-popup {
    max-width: 700px; /* Wider for letter */
    text-align: justify;
    font-family: var(--font-family-primary); /* Use serif font */
    background-color: #fdfbf5; /* Creamy background */
    border: 2px solid #c0b283; /* Gold-ish border */
    color: #4a4a4a; /* Dark grey text */
}
#ve-chung-toi-popup h2 {
    font-size: 1.8em;
    color: #8b4513; /* SaddleBrown */
    text-align: center;
    margin-bottom: 1.5rem;
    font-variant: small-caps;
    letter-spacing: 1px;
}
#ve-chung-toi-popup p {
    margin-bottom: 1.2rem;
    font-size: 1.1em;
    line-height: 1.7;
}

/* Newsletter Notification Popup */
#newsletter-notification-popup {
    max-width: 450px;
}
#newsletter-notification-popup h2 {
    color: var(--primary-color);
    font-size: 1.4em;
    margin-bottom: 1rem;
}
#newsletter-notification-popup p {
    font-size: 1rem;
    line-height: 1.6;
    color: #555;
    margin-bottom: 0.8rem;
}
#newsletter-notification-popup a {
    color: var(--primary-color);
    font-weight: bold;
}
#newsletter-notification-popup a:hover {
    color: var(--primary-color-darker);
}
#close-newsletter-popup-button {
    background-color: var(--primary-color);
    color: white;
    padding: 0.7rem 1.5rem;
    border-radius: 6px;
    font-size: 1rem;
    font-weight: bold;
    margin-top: 1rem;
}
#close-newsletter-popup-button:hover {
    background-color: var(--primary-color-darker);
}


/* --- Starfield (Only in Dark Mode) --- */
#starfield-sky {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  z-index: -1; /* Behind nav, behind overlay */
  display: none; /* Hidden by default */
  overflow: hidden; /* Crucial */
}
body.dark-mode #starfield-sky {
  display: block; /* Show stars only in dark mode */
}
.starfield-star {
  position: absolute;
  background-color: white;
  border-radius: 50%;
  opacity: 0; /* Start invisible */
  animation: starfield-twinkle 3s infinite ease-in-out alternate; /* Use alternate */
  box-shadow: 0 0 6px 2px rgba(255, 255, 255, 0.3); /* Subtle glow */
}
/* Vary star sizes and twinkle speeds */
.starfield-star:nth-child(5n) { width: 1px; height: 1px; animation-duration: 4s;}
.starfield-star:nth-child(5n+1) { width: 2px; height: 2px; animation-duration: 2.5s;}
.starfield-star:nth-child(5n+2) { width: 1.5px; height: 1.5px; animation-duration: 5s;}
.starfield-star:nth-child(5n+3) { width: 1px; height: 1px; animation-duration: 3.5s;}
.starfield-star:nth-child(5n+4) { width: 2.5px; height: 2.5px; animation-duration: 3s;}

@keyframes starfield-twinkle {
  0% { opacity: 0.1; transform: scale(0.8); } /* Dimmer start */
  100% { opacity: 0.9; transform: scale(1); } /* Brighter end */
}

/* --- Enhanced Shooting Star --- */
.starfield-shooting-star {
  position: absolute;
  height: 1.5px; /* Slightly thicker */
  /* Gradient: Brighter head (light cyan/blue tint), sharp fade */
  background: linear-gradient(to right, rgba(180, 220, 255, 0.95), transparent 75%);
  border-radius: 50%; /* Soft ends */
  filter: drop-shadow(0 0 6px rgba(150, 200, 255, 0.6)); /* Enhanced glow with tint */
  opacity: 0;
  /* Animation: Apply base animation */
  animation: starfield-shooting-star-flight 4s ease-in infinite; /* Use ease-in for acceleration feel */
  transform-origin: left center; /* Rotate from the head */
  z-index: 0; /* Above static stars but behind content */
}

/* Add predictable variations using :nth-child */
.starfield-shooting-star:nth-child(4n) {
  width: 120px; /* Longer */
  animation-duration: 5s; /* Faster */
  animation-delay: 0.5s;
}
.starfield-shooting-star:nth-child(4n+1) {
  width: 70px; /* Shorter */
  animation-duration: 6s; /* Slower */
  animation-delay: 1.2s;
  /* Slightly different gradient or glow could be added */
  background: linear-gradient(to right, rgba(255, 255, 200, 0.9), transparent 70%); /* Faint gold */
  filter: drop-shadow(0 0 5px rgba(255, 255, 180, 0.5));
}
.starfield-shooting-star:nth-child(4n+2) {
  width: 90px;
  animation-duration: 5s;
   animation-delay: 2s;
}
.starfield-shooting-star:nth-child(4n+3) {
  width: 100px; /* Default */
  animation-duration: 6s; /* Default */
  animation-delay: 0.1s; /* Almost immediate */
}


/* Keyframes for the flight path and fade */
@keyframes starfield-shooting-star-flight {
  0% {
    transform: translateX(110vw) translateY(-10vh) rotate(-35deg) scaleX(0.8);
    opacity: 0;
  }
  10% {
    transform: translateX(95vw) translateY(0vh) rotate(-35deg) scaleX(1);
    opacity: 1;
  }
  85% {
    transform: translateX(5vw) translateY(65vh) rotate(-35deg) scaleX(1);
    opacity: 1;
  }
  100% {
    transform: translateX(-10vw) translateY(80vh) rotate(-35deg) scaleX(0.8);
    opacity: 0;
  }
}

/* --- Scroll To Top Button --- */
#scrollToTop {
  position: fixed;
  bottom: 20px;
  right: 20px;
  background-color: rgba(90, 46, 152, 0.7); /* Semi-transparent */
  color: #fff;
  border: none;
  padding: 10px 12px; /* Adjust padding */
  border-radius: 50%; /* Circle */
  cursor: pointer;
  display: none; /* Hidden by default, shown by JS */
  transition: all 0.3s ease;
  z-index: 998; /* Below loading overlay */
  box-shadow: 0 2px 5px rgba(0,0,0,0.3);
  font-size: 1.2rem; /* Icon size */
  line-height: 1;
}
#scrollToTop:hover {
  background-color: rgba(90, 46, 152, 1); /* Solid on hover */
  transform: scale(1.1);
}
/* --- Styling cho số lượng sách trong submenu --- */
.category-count {
  font-size: 0.8em;          /* Kích thước nhỏ hơn chữ category */
  color: rgba(255, 255, 255, 0.7); /* Màu nhạt hơn */
  margin-left: 5px;          /* Khoảng cách với tên category */
  font-style: italic;        /* In nghiêng (tùy chọn) */
  font-weight: normal;       /* Không in đậm */
  white-space: nowrap;       /* Đảm bảo không xuống dòng */
}

/* --- Media Query for Mobile Responsiveness --- */
@media (max-width: 768px) {

  body {
    font-size: 14px; /* Slightly smaller base font */
  }

  .container {
    width: 100%; /* Use full width */
    padding: 0 5px; /* Minimal side padding */
  }

  h2 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
  }
  h3 {
      font-size: 1.1rem;
      margin-bottom: 0.6rem;
  }

  /* --- Mobile Navigation --- */
  #main-nav {
    /* Keep fixed, adjust internal layout */
  }

  #main-nav .nav-container {
      width: 100%;
      flex-direction: column; /* Stack sections vertically */
      align-items: center; /* Center items horizontally */
      padding: 5px;
  }

  .nav-section-left {
    display: none; /* Hide logo section */
  }

  .nav-section-right {
      padding: 0 5px; /* Minimal padding */
      width: 100%; /* Take full width */
      align-items: center; /* Center content */
  }

  .nav-sub-flow-top,
  .nav-sub-flow-middle,
  .nav-sub-flow-bottom {
      padding: 4px 0; /* Reduced vertical padding */
      justify-content: center; /* Center content */
      width: 100%;
  }

  .nav-sub-flow-top .site-title {
      font-size: 1.5em; /* Smaller title */
      white-space: normal; /* Allow wrapping if needed */
      text-align: center;
  }

  #main-nav .menu {
      gap: 4px 10px;
      justify-content: center;
      width: 100%;
      flex-wrap: wrap;
      padding-bottom: 0;
  }
  /* Hide specific less critical links on mobile */
  #main-nav .menu li a[data-section="lich-su-mua-hang"] {
      display: none;
  }

  #main-nav .menu > li > a {
      padding: 6px 8px; /* Smaller padding */
      font-size: 0.8rem; /* Smaller font */
      gap: 4px;
  }
   #main-nav .menu > li > a i {
       font-size: 0.8em;
   }
  #main-nav .submenu {
      min-width: 140px; /* Adjust width */
      transform: translateX(-50%) translateY(3px);
  }
  #main-nav .submenu a {
      padding: 8px 10px;
      font-size: 0.85rem;
  }

  .right-nav {
    flex-wrap: wrap; /* Allow wrapping */
    justify-content: center; /* Center items */
    gap: 8px; /* Reduced gap */
    width: 100%;
  }
  .nav-sub-flow-bottom {
      border-top: 1px solid rgba(255, 255, 255, 0.1);
      padding-top: 6px;
  }

  #user-info.interactive-van-xu {
      padding: 4px 8px;
      font-size: 0.8rem;
      gap: 5px;
      order: 1; /* Adjust order if needed */
  }

  .search-container {
      order: 2; /* Adjust order */
      flex-grow: 1; /* Allow search to take more space */
      max-width: 180px; /* Limit width */
  }
  #search-box {
      padding: 6px 30px 6px 10px;
      font-size: 0.8rem;
      width: 100%; /* Fill container */
  }
  #search-button {
      right: 8px;
      font-size: 0.9em;
  }
  #search-suggestions {
      font-size: 0.85rem; /* Adjust suggestion font */
  }

  .theme-toggle {
      order: 3;
  }
  .theme-toggle button {
      font-size: 1.3em; /* Slightly larger icon */
      padding: 5px;
  }

  .login-menu {
      order: 4;
  }
  #login-button, #logout-button {
      padding: 5px 10px;
      font-size: 0.8rem;
      gap: 4px;
  }

  /* --- Mobile Main Content --- */
  .main-content {
    padding-top: var(--nav-height-mobile); /* Adjust space for mobile nav */
  }

  /* Social Icons Mobile */
  .social-icons {
      gap: 15px;
      margin-bottom: 1.5rem;
  }
  .icon {
      width: 40px;
      height: 40px;
      font-size: 20px;
  }

  /* New Books Carousel Mobile */
  .new-books-carousel {
      max-width: 100%; /* Full width */
      margin: 0.5rem auto 1.5rem;
  }
  .new-book-item {
      aspect-ratio: 16 / 9; /* Common mobile aspect ratio */
  }
  .new-book-overlay {
      padding: 1rem 0.8rem 0.8rem;
  }
  .new-book-overlay h3 {
      font-size: 1.2em;
  }
  .new-book-overlay p {
      font-size: 0.8em;
  }

  /* Featured Carousel Mobile */
  .carousel {
      gap: 0.8rem;
      padding: 0.5rem 0.5rem 1rem;
  }
  .carousel-item {
      flex-basis: 150px; /* Smaller fixed width */
      min-height: 320px; /* Adjusted height */
  }

  /* Book Display Mobile */
  .book-container {
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr)); /* Adjust minmax */
    gap: 0.8rem; /* Reduced gap */
  }
  .book {
      min-height: 320px; /* Adjusted height */
      padding: 0.6rem;
  }
  .book-image {
      margin-bottom: 0.5rem;
  }
  .book-title-container {
      min-height: 2.8em;
      margin-bottom: 0.3rem;
  }
  .book h3 {
      font-size: 0.95em;
      line-height: 1.3;
  }
  .book-publication-date {
      font-size: 0.7em;
      margin-bottom: 0.3rem;
  }
  .ratings {
      margin-bottom: 0.5rem;
      transform: scale(0.9); /* Slightly smaller stars */
  }
  .book .purchase-button,
  .book .read-button {
      padding: 0.4rem 0.6rem;
      font-size: 0.75em;
  }
  .book .add-to-cart-button,
  .book .favorite-button {
      font-size: 1.1em;
      padding: 3px;
  }
  .button-group {
      gap: 0.3rem;
  }
  .button-row {
      gap: 0.3rem;
  }

  /* Pagination Mobile */
  .pagination {
      margin-top: 1.5rem;
      gap: 0.3rem;
  }
  .pagination button {
      padding: 0.4rem 0.7rem;
      font-size: 0.8rem;
  }

  /* Auth Forms Mobile */
  .auth-section {
      min-height: calc(100vh - var(--nav-height-mobile));
      padding: 1rem 0.5rem;
  }
  .form-container {
      padding: 1.5rem;
      width: 95%; /* Slightly inset */
  }
  .form-title { font-size: 1.5em; }
  .form-subtitle { font-size: 0.9em; margin-bottom: 1.5rem; }
  .input-group { margin-bottom: 1.5rem; }
  .form-input { padding: 0.8rem; font-size: 0.95em; }
  .input-label { left: 0.8rem; top: 0.8rem; }
  .form-input:focus + .input-label,
  .form-input:not(:placeholder-shown) + .input-label {
      top: -0.5rem;
      font-size: 0.75em;
  }
  .password-toggle-button { right: 0.6rem; font-size: 1em; }
  .remember-me-container { margin-bottom: 0.8rem; }
  .remember-me-container label { font-size: 0.85em; }
  .interactive-button, .sign-in-button { padding: 0.8rem 1.2rem; font-size: 1em; }
  .forgot-password-link { font-size: 0.85em; }
  .or-continue { margin: 1rem 0; font-size: 0.8em; }
  .social-button { width: 40px; height: 40px; font-size: 1.1em; }
  .form-footer { font-size: 0.9em; margin-top: 1rem; }

  /* History Table Mobile */
  #lich-su-mua-hang table {
      font-size: 0.8rem; /* Reduce overall table font size */
  }
  #lich-su-mua-hang th,
  #lich-su-mua-hang td {
      padding: 0.5rem 0.6rem; /* Reduced padding */
      white-space: nowrap; /* Prevent wrapping initially */
  }
  /* Consider making table horizontally scrollable if needed */
  #lich-su-mua-hang {
      overflow-x: auto; /* Add scroll if table too wide */
  }

  /* Book Details Mobile */
  .book-details-content {
      flex-direction: column; /* Stack elements */
      padding: 1rem;
      gap: 1.5rem;
  }
  #close-book-details-button {
      top: 0.5rem;
      right: 0.5rem;
      font-size: 1.5rem;
  }
  .book-cover {
      flex: 0 0 auto; /* Don't fix width */
      width: 60%; /* Cover takes significant width */
      margin: 0 auto; /* Center the cover */
      max-width: 200px; /* Limit max width */
  }
  .book-info {
      flex: 1; /* Take full width */
  }
  .book-info h2 { font-size: 1.6em; }
  .book-info p { font-size: 0.95rem; margin-bottom: 0.6rem; }
  .book-actions {
      gap: 0.6rem;
      justify-content: center; /* Center buttons */
      margin-top: 0.5rem;
      margin-bottom: 1rem;
  }
  .book-actions button {
      padding: 0.6rem 1rem;
      font-size: 0.9rem;
      gap: 6px;
  }
  .book-actions .tertiary-button {
      font-size: 1.4em;
  }
  .comments-section {
      margin-top: 1rem;
      padding-top: 1rem;
  }
  .comments-section h3 { font-size: 1.2em; }
  #book-details-comments { max-height: 150px; }
  #book-details-comment-box { font-size: 0.95rem; min-height: 60px; }
  #book-details-comment-submit { padding: 0.5rem 1rem; font-size: 0.9rem; }

  /* Footer Mobile */
  .site-footer {
      padding: 1.5rem 0.8rem 0.8rem;
      border-radius: 0; /* No rounding on mobile */
  }
  .footer-container {
      flex-direction: column; /* Stack sections */
      gap: 1.5rem;
      align-items: center; /* Center sections */
  }
  .footer-section {
      text-align: center; /* Center text */
      min-width: auto; /* Remove min-width */
      width: 100%; /* Full width */
  }
  .footer-title {
      font-size: 1rem;
      margin-bottom: 0.6rem;
  }
  .footer-section p {
      font-size: 0.85rem;
      margin-bottom: 0.6rem;
  }
  .footer-section ul {
      display: flex;
      flex-direction: column;
      align-items: center; /* Center links */
  }
  .footer-section ul li {
      margin-bottom: 0.4rem;
  }
  .footer-section ul li a {
      font-size: 0.85rem;
  }
  .footer-section .social-icons {
      justify-content: center; /* Center icons */
  }
  #newsletter-form {
      flex-direction: column; /* Stack input and button */
      align-items: stretch; /* Stretch items */
      gap: 0.5rem;
  }
  #newsletter-form input {
      flex: none;
      text-align: center;
      padding: 0.4rem 0.8rem; 
      height: auto;
  }
  .footer-bottom {
      margin-top: 1.5rem;
      padding-top: 1rem;
      font-size: 0.75rem;
  }
  .footer-bottom a {
      margin: 0 5px;
      gap: 3px;
  }

  /* Popups Mobile */
  .overlay > .form-container.glassmorphism {
      width: 95%; /* Slightly inset */
      padding: 1.5rem; /* Reduced padding */
      max-height: 90vh; /* Limit height */
      overflow-y: auto; /* Scroll if needed */
  }
  .overlay #payment-popup-close-icon,
  .overlay #close-ve-chung-toi-popup,
  .overlay #close-newsletter-popup-icon {
      top: 0.6rem;
      right: 0.6rem;
      font-size: 1.4rem;
  }
  #payment-popup h2 { font-size: 1.3em; }
  #payment-popup .account-info p { font-size: 1rem; }
  #payment-popup .account-info .account-number { font-size: 1.2rem; }
  #payment-popup .payment-instructions p { font-size: 0.95rem; }
  #payment-content-template { padding: 0.6rem; font-size: 0.9rem; }
  #reader-gmail { padding: 0.7rem; font-size: 0.95rem; }
  #copy-payment-content-button, #close-payment-popup { padding: 0.7rem 1.2rem; font-size: 0.9rem; }
  #ve-chung-toi-popup h2 { font-size: 1.5em; }
  #ve-chung-toi-popup p { font-size: 1em; }
  #newsletter-notification-popup h2 { font-size: 1.3em; }
  #newsletter-notification-popup p { font-size: 0.95rem; }
  #close-newsletter-popup-button { padding: 0.6rem 1.2rem; font-size: 0.95rem; }

  /* ScrollToTop Mobile */
  #scrollToTop {
      bottom: 15px;
      right: 15px;
      padding: 8px 10px;
      font-size: 1rem;
  }
}

/* Further adjustments for very small screens if needed */
@media (max-width: 480px) {
    .book-container {
        grid-template-columns: repeat(auto-fill, minmax(120px, 1fr)); /* Even smaller cards */
        gap: 0.6rem;
    }
    .book, .carousel-item {
        min-height: 280px; /* Adjust height again */
        padding: 0.5rem;
    }
    .book h3 {
        font-size: 0.85em;
    }
    .book-publication-date {
        font-size: 0.65em;
    }
    .ratings {
        transform: scale(0.8);
    }
    .book .purchase-button,
    .book .read-button {
        padding: 0.3rem 0.5rem;
        font-size: 0.7em;
    }
    .book .add-to-cart-button,
    .book .favorite-button {
        font-size: 1em;
    }

    .nav-sub-flow-top .site-title {
        font-size: 1.3em;
    }
    #main-nav .menu > li > a {
        padding: 5px 6px;
        font-size: 0.75rem;
    }
    #user-info.interactive-van-xu {
        font-size: 0.75rem;
    }
    #search-box {
        font-size: 0.75rem;
    }
    #login-button, #logout-button {
        font-size: 0.75rem;
        padding: 4px 8px;
    }

    .book-details-content {
        padding: 0.8rem;
    }
    .book-info h2 {
        font-size: 1.4em;
    }
    .book-info p {
        font-size: 0.9rem;
    }
    .book-actions button {
        padding: 0.5rem 0.8rem;
        font-size: 0.8rem;
    }

    .overlay > .form-container.glassmorphism {
        padding: 1rem;
    }

}