/**
 * Index Page - Blog-Style Design
 * Beautiful topic showcase with hero, cards, and filters
 */

/* ============================================
   HERO SECTION
   ============================================ */
.hero-section {
    background: linear-gradient(135deg, rgba(67, 97, 238, 0.9) 0%, rgba(114, 9, 183, 0.85) 100%),
        url('../images/wiki_hero_background.png') center/cover;
    color: #ffffff;
    padding: var(--space-12) var(--space-4);
    text-align: center;
    position: relative;
    overflow: hidden;
}

[data-theme="dark"] .hero-section {
    background: linear-gradient(135deg, rgba(26, 26, 26, 0.95) 0%, rgba(42, 42, 42, 0.9) 100%),
        url('../images/wiki_hero_background.png') center/cover;
}

[data-theme="premium"] .hero-section {
    background: linear-gradient(135deg, rgba(216, 69, 69, 0.9) 0%, rgba(114, 9, 183, 0.85) 100%),
        url('../images/wiki_hero_background.png') center/cover;
}

.hero-section::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: url('data:image/svg+xml,<svg width="60" height="60" xmlns="http://www.w3.org/2000/svg"><circle cx="30" cy="30" r="1" fill="white" opacity="0.1"/></svg>');
    opacity: 0.3;
}

.hero-content {
    position: relative;
    z-index: 1;
    max-width: 800px;
    margin: 0 auto;
}

.hero-title {
    font-size: var(--text-5xl);
    font-weight: var(--font-bold);
    margin-bottom: var(--space-4);
    line-height: var(--leading-tight);
}

.hero-subtitle {
    font-size: var(--text-xl);
    opacity: 0.9;
    margin-bottom: var(--space-8);
    line-height: var(--leading-relaxed);
}

.hero-search {
    max-width: 600px;
    margin: 0 auto;
    position: relative;
}

.hero-search-input {
    width: 100%;
    padding: var(--space-4) var(--space-6);
    padding-left: var(--space-12);
    font-size: var(--text-lg);
    border: none;
    border-radius: var(--radius-xl);
    background-color: rgba(255, 255, 255, 0.95);
    color: var(--text-primary);
    box-shadow: var(--shadow-lg);
    transition: box-shadow var(--transition-base);
}

.hero-search-input:focus {
    outline: none;
    box-shadow: var(--shadow-xl);
}

.hero-search-icon {
    position: absolute;
    left: var(--space-4);
    top: 50%;
    transform: translateY(-50%);
    font-size: var(--text-2xl);
    color: var(--text-muted);
}

/* ============================================
   FILTERS & CONTROLS
   ============================================ */
.controls-section {
    background-color: var(--bg-primary);
    padding: var(--space-6) 0;
    border-bottom: 1px solid var(--border-light);
    position: sticky;
    top: 56px;
    /* Below navbar */
    z-index: var(--z-sticky);
    box-shadow: var(--shadow-sm);
}

.controls-container {
    max-width: 1280px;
    margin: 0 auto;
    padding: 0 var(--space-8);
    display: flex;
    justify-content: space-between;
    align-items: center;
    gap: var(--space-4);
    flex-wrap: wrap;
}

.filter-group {
    display: flex;
    gap: var(--space-2);
    flex-wrap: wrap;
}

.filter-btn {
    padding: var(--space-2) var(--space-4);
    border: 1px solid var(--border-medium);
    background-color: var(--bg-primary);
    color: var(--text-secondary);
    border-radius: var(--radius-full);
    font-size: var(--text-sm);
    font-weight: var(--font-medium);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.filter-btn:hover {
    background-color: var(--bg-hover);
    border-color: var(--border-dark);
    color: var(--text-primary);
}

.filter-btn.active {
    background-color: var(--accent-primary);
    border-color: var(--accent-primary);
    color: var(--text-inverse);
}

.sort-dropdown {
    position: relative;
}

.sort-btn {
    padding: var(--space-2) var(--space-4);
    border: 1px solid var(--border-medium);
    background-color: var(--bg-primary);
    color: var(--text-secondary);
    border-radius: var(--radius-md);
    font-size: var(--text-sm);
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: var(--space-2);
    transition: all var(--transition-fast);
}

.sort-btn:hover {
    background-color: var(--bg-hover);
    border-color: var(--border-dark);
}

/* ============================================
   TOPICS GRID
   ============================================ */
.topics-section {
    padding: var(--space-8);
    max-width: 1280px;
    margin: 0 auto;
}

.topics-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(320px, 1fr));
    gap: var(--space-6);
    margin-top: var(--space-6);
}

/* ============================================
   TOPIC CARD
   ============================================ */
.topic-card {
    background-color: var(--bg-primary);
    border-radius: var(--radius-xl);
    overflow: hidden;
    box-shadow: var(--shadow-md);
    transition: transform var(--transition-base), box-shadow var(--transition-base);
    cursor: pointer;
    display: flex;
    flex-direction: column;
    height: 100%;
    border: 1px solid var(--border-light);
}

.topic-card:hover {
    transform: translateY(-6px);
    box-shadow: var(--shadow-xl);
}

.topic-card-cover {
    height: 180px;
    background: linear-gradient(135deg, var(--accent-primary) 0%, var(--accent-primary-hover) 100%);
    position: relative;
    overflow: hidden;
}

.topic-card-cover::before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    background: linear-gradient(180deg, transparent 0%, rgba(0, 0, 0, 0.3) 100%);
}

.topic-card-cover img {
    width: 100%;
    height: 100%;
    object-fit: cover;
}

/* Generate different gradient colors for variety */
.topic-card:nth-child(3n+1) .topic-card-cover {
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
}

.topic-card:nth-child(3n+2) .topic-card-cover {
    background: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
}

.topic-card:nth-child(3n+3) .topic-card-cover {
    background: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
}

.topic-card:nth-child(5n+1) .topic-card-cover {
    background: linear-gradient(135deg, #43e97b 0%, #38f9d7 100%);
}

.topic-card:nth-child(5n+2) .topic-card-cover {
    background: linear-gradient(135deg, #fa709a 0%, #fee140 100%);
}

.topic-card-body {
    padding: var(--space-5);
    flex: 1;
    display: flex;
    flex-direction: column;
}

.topic-card-title {
    font-size: var(--text-xl);
    font-weight: var(--font-bold);
    color: var(--text-primary);
    margin-bottom: var(--space-3);
    line-height: var(--leading-tight);
}

.topic-card-description {
    font-size: var(--text-sm);
    color: var(--text-secondary);
    line-height: var(--leading-relaxed);
    margin-bottom: var(--space-4);
    flex: 1;
    display: -webkit-box;
    -webkit-line-clamp: 3;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.topic-card-meta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: var(--space-3);
    padding-top: var(--space-3);
    border-top: 1px solid var(--border-light);
    font-size: var(--text-sm);
    color: var(--text-muted);
}

.topic-card-stats {
    display: flex;
    align-items: center;
    gap: var(--space-4);
}

.topic-card-stat {
    display: flex;
    align-items: center;
    gap: var(--space-1);
}

.topic-card-stat-icon {
    font-size: var(--text-base);
}

.topic-card-badge {
    padding: var(--space-1) var(--space-3);
    background-color: var(--accent-soft);
    color: var(--accent-primary);
    border-radius: var(--radius-full);
    font-size: var(--text-xs);
    font-weight: var(--font-medium);
}

/* ============================================
   EMPTY STATE
   ============================================ */
.empty-state {
    text-align: center;
    padding: var(--space-16) var(--space-4);
}

.empty-state-icon {
    font-size: 80px;
    margin-bottom: var(--space-4);
    opacity: 0.5;
}

.empty-state-title {
    font-size: var(--text-2xl);
    font-weight: var(--font-bold);
    color: var(--text-primary);
    margin-bottom: var(--space-2);
}

.empty-state-description {
    font-size: var(--text-base);
    color: var(--text-secondary);
    margin-bottom: var(--space-6);
    max-width: 500px;
    margin-left: auto;
    margin-right: auto;
}

.empty-state-action {
    display: inline-flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-3) var(--space-6);
    background-color: var(--accent-primary);
    color: var(--text-inverse);
    border-radius: var(--radius-lg);
    text-decoration: none;
    font-weight: var(--font-medium);
    transition: background-color var(--transition-fast);
}

.empty-state-action:hover {
    background-color: var(--accent-primary-hover);
}

/* ============================================
   LOADING SKELETON
   ============================================ */
.topic-card-skeleton {
    background-color: var(--bg-primary);
    border-radius: var(--radius-xl);
    overflow: hidden;
    border: 1px solid var(--border-light);
}

.topic-card-skeleton .skeleton-cover {
    height: 180px;
    background: var(--bg-secondary);
}

.topic-card-skeleton .skeleton-body {
    padding: var(--space-5);
}

.topic-card-skeleton .skeleton-title {
    height: 24px;
    width: 70%;
    margin-bottom: var(--space-3);
}

.topic-card-skeleton .skeleton-description {
    height: 16px;
    width: 100%;
    margin-bottom: var(--space-2);
}

.topic-card-skeleton .skeleton-meta {
    height: 20px;
    width: 40%;
    margin-top: var(--space-4);
}

/* ============================================
   RESPONSIVE
   ============================================ */
@media (max-width: 1024px) {
    .topics-grid {
        grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
        gap: var(--space-5);
    }
}

@media (max-width: 768px) {
    .hero-title {
        font-size: var(--text-4xl);
    }

    .hero-subtitle {
        font-size: var(--text-lg);
    }

    .hero-section {
        padding: var(--space-10) var(--space-4);
    }

    .controls-container {
        flex-direction: column;
        align-items: stretch;
        padding: 0 var(--space-4);
    }

    .filter-group {
        justify-content: center;
    }

    .topics-grid {
        grid-template-columns: 1fr;
        gap: var(--space-4);
    }

    .topics-section {
        padding: var(--space-6) var(--space-4);
    }

    .topic-card-cover {
        height: 150px;
    }
}

@media (max-width: 640px) {
    .hero-title {
        font-size: var(--text-3xl);
    }

    .hero-subtitle {
        font-size: var(--text-base);
    }

    .hero-search-input {
        font-size: var(--text-base);
        padding: var(--space-3) var(--space-5);
        padding-left: var(--space-10);
    }

    .topic-card-title {
        font-size: var(--text-lg);
    }
}