* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: #0a0a0a;
    color: #f0f0f0;
    min-height: 100vh;
    display: flex;
    flex-direction: column;
}

/* Đẩy nội dung chính mở rộng */
main {
    flex: 1 0 auto;
}

/* Định nghĩa màu sắc neon */
:root {
    --neon-cyan: #00e6ff;
    --neon-magenta: #ff00ff;
    --glow-cyan: rgba(0, 230, 255, 0.8);
    --glow-magenta: rgba(255, 0, 255, 0.8);
}

/* Header */
.header {
    background: #111111;
    padding: 15px;
    text-align: center;
    position: sticky;
    top: 0;
    z-index: 100;
    box-shadow: 0 0 20px var(--glow-cyan);
    border-bottom: 1px solid var(--neon-cyan);
}

.header a {
    color: #ffffff;
    text-decoration: none;
    margin: 0 20px;
    font-size: 18px;
    font-weight: 500;
    position: relative;
    transition: all 0.3s ease;
}

.header a:hover {
    color: var(--neon-cyan);
    text-shadow: 0 0 15px var(--glow-cyan);
}

.header a::after {
    content: '';
    position: absolute;
    width: 0;
    height: 2px;
    background: var(--neon-cyan);
    bottom: -5px;
    left: 50%;
    transform: translateX(-50%);
    transition: width 0.3s;
    box-shadow: 0 0 12px var(--glow-cyan);
}

.header a:hover::after {
    width: 100%;
}

/* Main Content */
.container {
    max-width: 1200px;
    margin: 30px auto;
    padding: 0 15px;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 25px;
}

.product-card {
    background: #1a1a1a;
    border-radius: 12px;
    padding: 20px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.5);
    transition: all 0.3s;
    position: relative;
    overflow: hidden;
    border: 1px solid #333;
    display: flex;
    flex-direction: column;
    height: 100%;
}

.product-card:hover {
    transform: translateY(-5px);
    box-shadow: 0 8px 20px rgba(0, 0, 0, 0.7), 0 0 20px var(--glow-cyan);
    border-color: var(--neon-cyan);
}

.product-card::after {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--neon-cyan), var(--neon-magenta), transparent);
}

.image-container {
    width: 100%;
    height: 180px;
    position: relative;
    border-radius: 8px;
    overflow: hidden;
    margin-bottom: 15px;
}

.product-card img {
    width: 100%;
    height: 100%;
    object-fit: cover;
    border-radius: 8px;
}

.price-tag {
    background: var(--neon-magenta);
    color: #000;
    padding: 6px 14px;
    border-radius: 20px;
    font-size: 16px;
    font-weight: 600;
    box-shadow: 0 0 15px var(--glow-magenta);
    position: absolute;
    top: 10px;
    right: 10px;
}

.product-card h3 {
    margin: 10px 0 5px;
    font-size: 20px;
    color: #ffffff;
    font-weight: 600;
}

.product-card p {
    margin: 5px 0 10px;
    font-size: 16px;
    color: #aaaaaa;
    line-height: 1.4;
}

.product-card ul {
    list-style: none;
    text-align: left;
    margin: 10px 0;
    flex-grow: 1;
}

.product-card ul li {
    margin: 8px 0;
    font-size: 14px;
    color: #cccccc;
    position: relative;
    padding-left: 25px;
}

.product-card ul li .checkmark {
    color: var(--neon-cyan);
    position: absolute;
    left: 0;
    font-size: 16px;
    text-shadow: 0 0 5px var(--glow-cyan);
}

.product-card button {
    background: linear-gradient(to right, var(--neon-cyan), var(--neon-magenta));
    border: none;
    padding: 12px 24px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    color: #000;
    transition: all 0.3s;
    box-shadow: 0 0 15px var(--glow-cyan);
    margin-top: auto;
}

.product-card button:hover {
    transform: translateY(-2px);
    box-shadow: 0 0 25px var(--glow-magenta);
}

/* Login Styles */
.login-container {
    max-width: 400px;
    margin: 50px auto;
    padding: 30px;
    background: #1a1a1a;
    border-radius: 10px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.5), 0 0 20px var(--glow-cyan);
    border: 1px solid var(--neon-cyan);
    position: relative;
    overflow: hidden;
}

.login-container::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--neon-cyan), var(--neon-magenta), transparent);
}

.login-container h2 {
    text-align: center;
    margin-bottom: 25px;
    color: #ffffff;
    font-weight: 600;
    font-size: 24px;
}

/* Dashboard Styles */
.dashboard-container {
    max-width: 600px;
    margin: 30px auto;
    padding: 30px;
    background: #1a1a1a;
    border-radius: 10px;
    box-shadow: 0 10px 25px rgba(0, 0, 0, 0.5), 0 0 20px var(--glow-cyan);
    border: 1px solid var(--neon-cyan);
    position: relative;
    overflow: hidden;
}

.dashboard-container::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, transparent, var(--neon-cyan), var(--neon-magenta), transparent);
}

.dashboard-container h2 {
    text-align: center;
    margin-bottom: 25px;
    color: #ffffff;
    font-weight: 600;
    font-size: 24px;
}

.form-group {
    margin-bottom: 20px;
}

.form-group label {
    display: block;
    margin-bottom: 8px;
    font-size: 16px;
    color: #cccccc;
}

.form-group input,
.form-group textarea {
    width: 100%;
    padding: 12px;
    border-radius: 6px;
    border: 1px solid #333;
    background: #0f0f0f;
    color: #fff;
    font-size: 16px;
    transition: all 0.3s;
}

.form-group input:focus,
.form-group textarea:focus {
    border-color: var(--neon-cyan);
    box-shadow: 0 0 0 2px var(--glow-cyan);
    outline: none;
}

.form-group textarea {
    min-height: 120px;
    resize: vertical;
}

.login-container button,
.dashboard-container button {
    background: linear-gradient(to right, var(--neon-cyan), var(--neon-magenta));
    border: none;
    padding: 12px 20px;
    border-radius: 6px;
    cursor: pointer;
    font-size: 18px;
    font-weight: 600;
    color: #000;
    display: block;
    width: 100%;
    transition: all 0.3s;
    box-shadow: 0 0 15px var(--glow-cyan);
}

.login-container button:hover,
.dashboard-container button:hover {
    transform: translateY(-2px);
    box-shadow: 0 0 25px var(--glow-magenta);
}

#logout-btn {
    background: linear-gradient(to right, #ff3d3d, #ff7070);
    border: none;
    padding: 7px 18px;
    border-radius: 4px;
    color: #fff;
    cursor: pointer;
    font-weight: 500;
    margin-left: 15px;
    transition: all 0.3s;
    box-shadow: 0 0 10px rgba(255, 61, 61, 0.5);
    font-size: 16px;
}

#logout-btn:hover {
    transform: translateY(-2px);
    box-shadow: 0 0 15px rgba(255, 61, 61, 0.7);
}

/* Footer */
.footer {
    background: #111111;
    padding: 15px;
    text-align: center;
    border-top: 1px solid var(--neon-cyan);
    flex-shrink: 0;
    box-shadow: 0 0 20px var(--glow-cyan);
}

.footer p {
    color: #aaaaaa;
    margin-bottom: 10px;
    text-shadow: 0 0 5px var(--glow-cyan);
    font-size: 16px;
}

.footer a {
    color: #ffffff;
    text-decoration: none;
    margin: 0 10px;
    position: relative;
    transition: all 0.3s;
    font-size: 16px;
}

.footer a:hover {
    color: var(--neon-magenta);
    text-shadow: 0 0 15px var(--glow-magenta);
}

/* Responsive */
@media (max-width: 768px) {
    .container {
        grid-template-columns: 1fr;
    }

    .header a {
        display: inline-block;
        margin: 5px 10px;
    }
}