/**
 * category-index.css
 * Shared styles for all category index pages (education, literatures, AI_Academy, etc.)
 * Each page only needs to set CSS custom properties for its color scheme.
 */

/* ── Base ───────────────────────────────────────────────────────────────── */

body {
    font-family: 'Noto Sans TC', sans-serif;
    line-height: 1.6;
    color: var(--text-color, #333);
    background-color: var(--bg-color, #f0f4f8);
    margin: 0;
    padding: 0;
}

/* ── Hero ───────────────────────────────────────────────────────────────── */

.hero {
    position: relative;
    background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
    color: white;
    padding: 40px 20px;
    text-align: center;
    box-shadow: 0 4px 10px rgba(0, 0, 0, 0.1);
}

.hero h1 {
    margin: 0;
    font-size: 2rem;
    letter-spacing: 2px;
}

.hero p {
    margin: 10px 0 0 0;
    font-size: 1.1rem;
    opacity: 0.9;
}

.back-btn {
    position: absolute;
    top: 15px;
    left: 15px;
    background: rgba(255, 255, 255, 0.2);
    color: white;
    padding: 8px 16px;
    border-radius: 20px;
    text-decoration: none;
    font-size: 0.9rem;
    transition: background 0.2s;
}

.back-btn:hover {
    background: rgba(255, 255, 255, 0.3);
}

/* ── Layout ─────────────────────────────────────────────────────────────── */

.container {
    max-width: 900px;
    margin: 0 auto;
    padding: 20px;
}

.intro-text {
    text-align: center;
    margin-bottom: 30px;
    color: #555;
}

/* ── Card Grid ──────────────────────────────────────────────────────────── */

.topic-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(224px, 1fr));
    gap: 16px;
}

.topic-card {
    background: var(--card-bg, #ffffff);
    border-radius: 12px;
    padding: 16px;
    text-decoration: none;
    color: inherit;
    display: flex;
    flex-direction: column;
    transition: all 0.3s ease;
    border: 1px solid var(--card-border, #e1e8ed);
    position: relative;
    overflow: hidden;
}

.topic-card:hover {
    transform: translateY(-4px);
    box-shadow: 0 6px 12px rgba(0, 0, 0, 0.1);
    border-color: var(--primary-color);
}

.topic-card:focus-visible {
    outline: 3px solid var(--primary-color);
    outline-offset: 2px;
}

.topic-icon {
    font-size: 2rem;
    margin-bottom: 10px;
}

.topic-title {
    font-size: 1rem;
    font-weight: bold;
    color: var(--primary-color);
    margin-bottom: 6px;
}

.topic-desc {
    font-size: 0.8rem;
    color: #666;
    flex-grow: 1;
}

/* ── Badges ─────────────────────────────────────────────────────────────── */

.topic-badge {
    position: absolute;
    top: 8px;
    right: -26px;
    background: var(--accent-color, #10b981);
    color: white;
    padding: 4px 30px;
    font-size: 10px;
    transform: rotate(45deg);
}

.topic-card.pdf::after {
    content: "PDF";
    position: absolute;
    top: 8px;
    right: -22px;
    background: #ef4444;
    color: white;
    padding: 4px 26px;
    font-size: 10px;
    transform: rotate(45deg);
}

.topic-card.completed::after {
    content: "已上線";
    position: absolute;
    top: 8px;
    right: -26px;
    background: var(--accent-color);
    color: white;
    padding: 4px 30px;
    font-size: 10px;
    transform: rotate(45deg);
}

.topic-card.pending {
    opacity: 0.7;
    background-color: #fafafa;
    border-style: dashed;
}

/* ── Footer ─────────────────────────────────────────────────────────────── */

footer {
    text-align: center;
    padding: 40px 20px;
    color: #888;
    font-size: 0.9rem;
}

/* ── Topic Filter Bar ───────────────────────────────────────────────────── */

.topic-filter-bar {
    display: flex;
    flex-wrap: wrap;
    gap: 8px;
    margin-bottom: 20px;
    justify-content: center;
}

.topic-filter-btn {
    padding: 6px 14px;
    border: 1px solid #d1d5db;
    border-radius: 20px;
    background: white;
    color: #64748b;
    font-size: 0.8rem;
    cursor: pointer;
    transition: all 0.2s;
    font-family: inherit;
}

.topic-filter-btn:hover {
    border-color: var(--primary-color);
    color: var(--primary-color);
}

.topic-filter-btn.active {
    background: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}

/* ── NEW Badge ──────────────────────────────────────────────────────────── */

.new-badge {
    background: #ef4444 !important;
    font-weight: 700;
    letter-spacing: 1px;
}

/* ── Responsive ─────────────────────────────────────────────────────────── */

@media (max-width: 480px) {
    .hero h1 {
        font-size: 1.5rem;
    }

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