:root {
    --primary-color: #2c3e50;
    --secondary-color: #3498db;
    --accent-color: #e74c3c;
    --text-color: #2c3e50;
    --light-bg: #ecf0f1;
    --white: #ffffff;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    line-height: 1.6;
    color: var(--text-color);
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 20px;
}

/* Navbar */
.navbar {
    background: var(--primary-color);
    padding: 1rem 0;
    width: 100%;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
    height: 72px;
}

.navbar .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 100%;
}

.logo {
    color: var(--white);
    font-size: 1.5rem;
    font-weight: bold;
}

.nav-links {
    display: flex;
    gap: 2rem;
}

.nav-links a {
    color: var(--white);
    text-decoration: none;
    transition: all 0.3s ease;
    font-size: 1rem;
    padding: 0.5rem 1rem;
    border-radius: 4px;
}

.nav-links a:hover {
    color: var(--white);
    background: rgba(255, 255, 255, 0.1);
}

.nav-links a[href="#about"]:hover {
    color: var(--white);
    background: rgba(255, 255, 255, 0.2);
}

/* Hero Section */
.hero {
    min-height: calc(100vh - 72px);
    margin-top: 0;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    display: flex;
    align-items: center;
    text-align: center;
    color: var(--white);
    perspective: 1000px;
    transition: filter 0.3s ease;
}

.hero-content {
    transform-style: preserve-3d;
    animation: float 6s ease-in-out infinite;
}

.profile-image {
    width: 200px;
    height: 200px;
    margin: 0 auto 2rem;
    border-radius: 50%;
    overflow: hidden;
    border: 4px solid var(--white);
    box-shadow: 0 10px 20px rgba(0,0,0,0.2);
}

.profile-image img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

.hero h1 {
    font-size: 3rem;
    margin-bottom: 1rem;
    transform: translateZ(50px);
}

.hero h2 {
    font-size: 2rem;
    margin-bottom: 1rem;
    transform: translateZ(30px);
}

.about {
    padding: 100px 0;
    background: var(--white);
}

.about-content {
    display: grid;
    grid-template-columns: 1fr 2fr;
    gap: 2rem;
    align-items: center;
}

.about-image img {
    width: 100%;
    border-radius: 10px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
    transform: perspective(1000px) rotateY(-5deg);
    transition: transform 0.3s ease;
}

.about-image img:hover {
    transform: perspective(1000px) rotateY(0deg);
}

.research {
    padding: 100px 0;
    background: var(--light-bg);
}

.research-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.research-item {
    position: relative;
    overflow: hidden;
    background: var(--white);
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
    transform: translateZ(0);
    transition: transform 0.3s ease;
}

.research-item:hover {
    transform: translateY(-10px);
}

.research-images {
    position: relative;
    width: 100%;
    height: 200px;
    overflow: hidden;
    margin-bottom: 1rem;
}

.research-images img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    object-fit: cover;
    opacity: 0;
    transition: opacity 0.5s ease;
}

.research-images img.active {
    opacity: 1;
}

.teaching {
    padding: 100px 0;
    background: var(--white);
}

.teaching-content {
    display: grid;
    grid-template-columns: 1fr;
    gap: 2rem;
}

.teaching-gallery {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1rem;
    margin-bottom: 2rem;
}

.teaching-gallery img {
    width: 100%;
    height: 200px;
    object-fit: cover;
    border-radius: 10px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
    transition: transform 0.3s ease;
}

.teaching-gallery img:hover {
    transform: scale(1.05);
}

.tutoring-request form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
    max-width: 600px;
    margin: 0 auto;
}

.tutoring-request input,
.tutoring-request select,
.tutoring-request textarea {
    padding: 1rem;
    border: 1px solid #ddd;
    border-radius: 5px;
    font-size: 1rem;
}

.btn {
    background: var(--secondary-color);
    color: var(--white);
    padding: 1rem 2rem;
    border: none;
    border-radius: 5px;
    cursor: pointer;
    text-decoration: none;
    display: inline-block;
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
}

.contact {
    padding: 100px 0;
    background: var(--light-bg);
}

.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 2rem;
    margin-top: 2rem;
}

.contact-item {
    text-align: center;
    padding: 2rem;
    background: var(--white);
    border-radius: 10px;
    box-shadow: 0 10px 20px rgba(0,0,0,0.1);
    transform: translateZ(0);
    transition: transform 0.3s ease;
    cursor: pointer;
    text-decoration: none;
    display: block;
}

.contact-item:hover {
    transform: translateY(-5px);
}

.contact-item i {
    font-size: 2rem;
    color: var(--secondary-color);
    margin-bottom: 1rem;
}

.contact-item a {
    color: var(--text-color);
    text-decoration: none;
}

h2 {
    text-align: center;
    font-size: 2.5rem;
    margin-bottom: 3rem;
    color: var(--primary-color);
    position: relative;
}

h2:after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 50%;
    transform: translateX(-50%);
    width: 100px;
    height: 3px;
    background: var(--secondary-color);
}

h3 {
    text-align: center;
    font-size: 1.8rem;
    margin-bottom: 2rem;
    color: var(--primary-color);
}

#goToTop {
    position: fixed;
    bottom: 30px;
    right: 30px;
    width: 50px;
    height: 50px;
    background: var(--secondary-color);
    color: var(--white);
    border-radius: 50%;
    display: none;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
    transition: all 0.3s ease;
    z-index: 1000;
}

#goToTop:hover {
    transform: translateY(-5px);
    background: var(--primary-color);
}

.email-btn {
    position: fixed;
    left: 0;
    top: 50%;
    transform: translateY(-50%);
    background: #e74c3c;
    color: var(--white);
    width: 50px;
    height: 50px;
    display: flex;
    justify-content: center;
    align-items: center;
    cursor: pointer;
    transition: all 0.3s ease;
    z-index: 1000;
    border-radius: 0 5px 5px 0;
}

.email-btn:hover {
    width: 55px;
}

.email-btn .tooltip {
    position: fixed;
    left: 60px;
    background: var(--primary-color);
    color: var(--white);
    padding: 8px 16px;
    border-radius: 4px;
    font-size: 0.9rem;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    white-space: nowrap;
}

.email-btn .tooltip.show {
    opacity: 1;
    visibility: visible;
}

.lang-switcher {
    position: fixed;
    left: 30px;
    bottom: 30px;
    z-index: 1000;
}

.lang-btn {
    background: var(--secondary-color);
    color: var(--white);
    border: none;
    width: 50px;
    height: 50px;
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 5px 15px rgba(0,0,0,0.2);
    transition: all 0.3s ease;
    font-weight: bold;
}

.lang-btn:hover {
    transform: scale(1.1);
}

.hero.blur {
    filter: blur(5px);
}

.hamburger {
    display: none;
    flex-direction: column;
    gap: 4px;
    cursor: pointer;
    padding: 10px;
}

.hamburger span {
    display: block;
    width: 25px;
    height: 2px;
    background: var(--white);
    transition: all 0.3s ease;
}

.form-notification {
    position: fixed;
    right: 20px;
    top: 20px;
    background: var(--secondary-color);
    color: var(--white);
    padding: 15px 25px;
    border-radius: 4px;
    font-size: 0.9rem;
    opacity: 0;
    visibility: hidden;
    transition: all 0.3s ease;
    z-index: 1000;
}

.form-notification.show {
    opacity: 1;
    visibility: visible;
}

@media (max-width: 768px) {
    .nav-links {
        display: none;
        position: fixed;
        top: 70px;
        left: 0;
        width: 100%;
        background: var(--primary-color);
        flex-direction: column;
        padding: 20px 0;
        z-index: 1000;
        box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
    }

    .nav-links.active {
        display: flex;
    }

    .nav-links a {
        padding: 15px 20px;
        width: 100%;
        text-align: center;
    }

    .hamburger {
        display: flex;
        flex-direction: column;
        gap: 6px;
        cursor: pointer;
        padding: 10px;
        z-index: 1001;
    }

    .hamburger span {
        display: block;
        width: 25px;
        height: 2px;
        background: var(--white);
        transition: all 0.3s ease;
    }

    .hamburger.active span:nth-child(1) {
        transform: rotate(45deg) translate(6px, 6px);
    }

    .hamburger.active span:nth-child(2) {
        opacity: 0;
    }

    .hamburger.active span:nth-child(3) {
        transform: rotate(-45deg) translate(6px, -6px);
    }

    .about-content {
        grid-template-columns: 1fr;
    }

    .hero h1 {
        font-size: 2rem;
    }

    .hero h2 {
        font-size: 1.5rem;
    }

    .profile-image {
        width: 150px;
        height: 150px;
    }

    .teaching-gallery {
        grid-template-columns: 1fr;
    }
}

.section-title {
    position: relative;
    transform-style: preserve-3d;
    perspective: 1000px;
}

.section-title::after {
    content: '';
    position: absolute;
    bottom: -10px;
    left: 0;
    width: 100%;
    height: 2px;
    background: var(--secondary-color);
    transform: translateZ(-10px);
}

@keyframes float {
    0%, 100% {
        transform: translateY(0);
    }
    50% {
        transform: translateY(-20px);
    }
}

footer {
    background: var(--primary-color);
    color: var(--white);
    padding: 2rem 0;
    text-align: center;
    position: relative;
    clip-path: polygon(0 15%, 100% 0, 100% 100%, 0 100%);
    padding-top: 5rem;
}

footer .container {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

footer p {
    margin: 0;
    font-size: 1rem;
    opacity: 0.9;
}

footer a {
    color: var(--secondary-color);
    text-decoration: none;
    transition: color 0.3s ease;
}

footer a:hover {
    color: var(--white);
}

footer .heart {
    color: #ff0000;
    display: inline-block;
    animation: heartbeat 1.5s infinite;
}

@keyframes heartbeat {
    0%, 100% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.2);
    }
}