:root {
    --primary-color: #E53935;
    --primary-dark: #C62828;
    --accent-color: #FF6F00;
    --text-dark: #1A1A1A;
    --text-light: #666666;
    --bg-dark: #121212;
    --bg-light: #F5F5F5;
    --white: #FFFFFF;
    --border-color: #E0E0E0;
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
    --shadow-hover: 0 8px 30px rgba(229, 57, 53, 0.25);
}

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

body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
    line-height: 1.6;
    color: var(--text-dark);
    background-color: var(--bg-light);
}

a {
    text-decoration: none;
    color: inherit;
    transition: color 0.3s ease;
}

ul {
    list-style: none;
}

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

/* Header & Navigation */
header {
    background: var(--white);
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.1);
    position: sticky;
    top: 0;
    z-index: 1000;
}

nav {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 15px 0;
}

.logo {
    font-size: 28px;
    font-weight: 800;
    color: var(--primary-color);
}

.logo span {
    color: var(--primary-dark);
}

.nav-links {
    display: flex;
    gap: 30px;
}

.nav-links a {
    font-size: 16px;
    font-weight: 600;
    position: relative;
    padding: 5px 0;
    color: var(--text-dark);
}

.nav-links a:hover,
.nav-links a.active {
    color: var(--primary-color);
}

.nav-links a::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 0;
    height: 3px;
    background: var(--primary-color);
    transition: width 0.3s ease;
}

.nav-links a:hover::after,
.nav-links a.active::after {
    width: 100%;
}

/* Hero Section */
.hero {
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--primary-dark) 100%);
    color: var(--white);
    padding: 100px 0;
    text-align: center;
}

.hero h1 {
    font-size: 48px;
    font-weight: 800;
    margin-bottom: 20px;
    animation: fadeInUp 0.8s ease;
}

.hero p {
    font-size: 20px;
    margin-bottom: 40px;
    opacity: 0.95;
    animation: fadeInUp 0.8s ease 0.2s both;
}

.hero .cta-buttons {
    display: flex;
    gap: 20px;
    justify-content: center;
    animation: fadeInUp 0.8s ease 0.4s both;
}

.btn {
    display: inline-block;
    padding: 14px 36px;
    border-radius: 8px;
    font-weight: 700;
    font-size: 16px;
    cursor: pointer;
    transition: all 0.3s ease;
    border: none;
}

.btn-primary {
    background: var(--white);
    color: var(--primary-color);
}

.btn-primary:hover {
    background: var(--bg-light);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(255, 255, 255, 0.3);
}

.btn-secondary {
    background: transparent;
    color: var(--white);
    border: 2px solid var(--white);
}

.btn-secondary:hover {
    background: var(--white);
    color: var(--primary-color);
}

/* Section Styles */
.section {
    padding: 80px 0;
}

.section-title {
    text-align: center;
    margin-bottom: 50px;
}

.section-title h2 {
    font-size: 36px;
    color: var(--text-dark);
    margin-bottom: 15px;
    font-weight: 700;
}

.section-title p {
    color: var(--text-light);
    font-size: 18px;
}

/* Card Styles */
.card-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 25px;
}

.card {
    background: var(--white);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow);
    transition: all 0.3s ease;
}

.card:hover {
    transform: translateY(-8px);
    box-shadow: var(--shadow-hover);
}

.card-image {
    width: 100%;
    height: 200px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    font-size: 48px;
    position: relative;
}

.card-image .play-icon {
    font-size: 60px;
    opacity: 0.9;
}

.card-content {
    padding: 25px;
}

.card-content h3 {
    font-size: 20px;
    margin-bottom: 12px;
    color: var(--text-dark);
    font-weight: 700;
    line-height: 1.4;
}

.card-content .meta {
    color: var(--text-light);
    font-size: 14px;
    margin-bottom: 15px;
    display: flex;
    gap: 20px;
    align-items: center;
}

.hot-tag {
    background: var(--primary-color);
    color: var(--white);
    padding: 3px 10px;
    border-radius: 4px;
    font-size: 12px;
    font-weight: 600;
}

.card-content p {
    color: var(--text-light);
    margin-bottom: 20px;
    font-size: 15px;
}

.card-link {
    color: var(--primary-color);
    font-weight: 700;
    display: inline-flex;
    align-items: center;
    gap: 8px;
}

.card-link:hover {
    gap: 12px;
}

/* Video Card Special */
.video-card .card-image {
    cursor: pointer;
}

.video-card .card-image::after {
    content: '▶';
    position: absolute;
    font-size: 50px;
    opacity: 0.8;
}

/* Table Styles */
.table-container {
    background: var(--white);
    border-radius: 12px;
    overflow: hidden;
    box-shadow: var(--shadow);
}

table {
    width: 100%;
    border-collapse: collapse;
}

thead {
    background: var(--primary-color);
    color: var(--white);
}

th, td {
    padding: 18px 20px;
    text-align: left;
}

tbody tr {
    border-bottom: 1px solid var(--border-color);
}

tbody tr:hover {
    background: var(--bg-light);
}

.rank-badge {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 36px;
    height: 36px;
    border-radius: 50%;
    background: var(--primary-color);
    color: var(--white);
    font-weight: 700;
}

.rank-1 {
    background: #FFD700;
    color: var(--text-dark);
}

.rank-2 {
    background: #C0C0C0;
}

.rank-3 {
    background: #CD7F32;
}

/* FAQ Styles */
.faq-item {
    background: var(--white);
    margin-bottom: 15px;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 2px 10px rgba(0, 0, 0, 0.08);
}

.faq-question {
    padding: 20px 25px;
    background: var(--white);
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    font-weight: 700;
    font-size: 18px;
}

.faq-answer {
    padding: 0 25px 20px;
    color: var(--text-light);
    display: none;
}

.faq-item.active .faq-answer {
    display: block;
}

/* About Section */
.about-content {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 60px;
    align-items: center;
}

.about-text h2 {
    font-size: 32px;
    margin-bottom: 20px;
    font-weight: 700;
}

.about-text p {
    margin-bottom: 20px;
    color: var(--text-light);
}

.about-image {
    height: 400px;
    background: linear-gradient(135deg, var(--primary-color) 0%, var(--accent-color) 100%);
    border-radius: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--white);
    font-size: 80px;
}

/* Footer */
footer {
    background: var(--bg-dark);
    color: var(--white);
    padding: 60px 0 30px;
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 40px;
    margin-bottom: 40px;
}

.footer-section h3 {
    font-size: 20px;
    margin-bottom: 20px;
    font-weight: 700;
}

.footer-section ul li {
    margin-bottom: 12px;
}

.footer-section ul li a:hover {
    color: var(--primary-color);
}

.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.6);
}

/* Animations */
@keyframes fadeInUp {
    from {
        opacity: 0;
        transform: translateY(30px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}

/* Topic Card */
.topic-card .card-content {
    text-align: center;
}

.topic-count {
    font-size: 36px;
    font-weight: 800;
    color: var(--primary-color);
    margin-bottom: 10px;
}

/* Responsive Design */
@media (max-width: 768px) {
    .nav-links {
        display: none;
    }

    .hero h1 {
        font-size: 32px;
    }

    .hero p {
        font-size: 16px;
    }

    .hero .cta-buttons {
        flex-direction: column;
    }

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

    .card-grid {
        grid-template-columns: 1fr;
    }
}