/* ============================================
   SHRM Course Website — Core Styles
   ============================================ */

:root {
    --bg: #0d0d1a;
    --surface: #16162a;
    --surface-hover: #1e1e3a;
    --text: #e0e0f0;
    --text-light: #9090b0;
    --text-muted: #606080;
    --border: #2a2a4a;
    --border-light: #3a3a5a;
    --primary: #6c5ce7;
    --primary-light: #a29bfe;
    --primary-dark: #4834d4;
    --accent: #00cec9;
    --accent-light: #81ecec;
    --lecture-badge: #6c5ce7;
    --tutorial-badge: #00b894;
    --success: #00b894;
    --warning: #fdcb6e;
    --danger: #e17055;
    --font-main: 'Segoe UI', system-ui, -apple-system, sans-serif;
    --font-mono: 'JetBrains Mono', 'Fira Code', monospace;
    --radius: 12px;
    --radius-sm: 8px;
    --radius-lg: 16px;
    --shadow: 0 4px 20px rgba(0, 0, 0, 0.3);
    --shadow-hover: 0 8px 30px rgba(108, 92, 231, 0.2);
    --transition: all 0.3s ease;
}

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

html {
    scroll-behavior: smooth;
}

body {
    font-family: var(--font-main);
    background: var(--bg);
    color: var(--text);
    line-height: 1.6;
    min-height: 100vh;
}

a {
    color: var(--primary-light);
    text-decoration: none;
    transition: var(--transition);
}

a:hover {
    color: var(--accent-light);
}

/* ===== Header ===== */
.site-header {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 0 2rem;
    position: sticky;
    top: 0;
    z-index: 100;
    backdrop-filter: blur(10px);
}

.header-inner {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 64px;
}

.site-logo {
    display: flex;
    align-items: center;
    gap: 12px;
    font-size: 1.1rem;
    font-weight: 700;
    color: var(--text);
}

.site-logo .logo-icon {
    width: 36px;
    height: 36px;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    border-radius: var(--radius-sm);
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 1.2rem;
}

.main-nav {
    display: flex;
    gap: 24px;
    align-items: center;
}

.main-nav a {
    color: var(--text-light);
    font-size: 0.9rem;
    font-weight: 500;
}

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

/* ===== Hero Section ===== */
.hero {
    background: linear-gradient(135deg, #1a1a3e 0%, #2c1f52 40%, #0d0d1a 100%);
    padding: 60px 2rem;
    text-align: center;
    position: relative;
    overflow: hidden;
}

.hero::before {
    content: '';
    position: absolute;
    top: -50%;
    left: -50%;
    width: 200%;
    height: 200%;
    background: radial-gradient(circle at 30% 50%, rgba(108, 92, 231, 0.08) 0%, transparent 60%),
                radial-gradient(circle at 70% 50%, rgba(0, 206, 201, 0.06) 0%, transparent 60%);
    pointer-events: none;
}

.hero-content {
    max-width: 900px;
    margin: 0 auto;
    position: relative;
    z-index: 1;
}

.hero-code {
    display: inline-block;
    background: rgba(108, 92, 231, 0.2);
    color: var(--primary-light);
    padding: 4px 16px;
    border-radius: 20px;
    font-size: 0.85rem;
    font-weight: 600;
    margin-bottom: 16px;
    border: 1px solid rgba(108, 92, 231, 0.3);
}

.hero h1 {
    font-size: 2.8rem;
    font-weight: 800;
    margin-bottom: 12px;
    background: linear-gradient(135deg, #fff 0%, var(--primary-light) 50%, var(--accent-light) 100%);
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.hero-subtitle {
    font-size: 1.2rem;
    color: var(--text-light);
    margin-bottom: 24px;
}

.hero-meta {
    display: flex;
    justify-content: center;
    gap: 32px;
    flex-wrap: wrap;
}

.hero-meta-item {
    display: flex;
    align-items: center;
    gap: 8px;
    color: var(--text-light);
    font-size: 0.9rem;
}

.hero-meta-item .icon {
    font-size: 1.1rem;
}

/* ===== Progress Stats ===== */
.progress-stats {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 20px 2rem;
}

.stats-inner {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    gap: 32px;
    flex-wrap: wrap;
    justify-content: center;
}

.stat-item {
    text-align: center;
    padding: 8px 24px;
    background: rgba(255,255,255,0.03);
    border-radius: var(--radius-sm);
    border: 1px solid var(--border);
}

.stat-number {
    font-size: 1.8rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
}

.stat-label {
    font-size: 0.8rem;
    color: var(--text-light);
    margin-top: 2px;
}

/* ===== Filters ===== */
.filter-bar {
    background: var(--surface);
    border-bottom: 1px solid var(--border);
    padding: 16px 2rem;
    position: sticky;
    top: 64px;
    z-index: 50;
}

.filter-inner {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    gap: 16px;
    flex-wrap: wrap;
    align-items: center;
}

.filter-label {
    font-size: 0.85rem;
    color: var(--text-light);
    font-weight: 600;
    margin-right: 4px;
}

.filter-group {
    display: flex;
    gap: 8px;
    flex-wrap: wrap;
}

.filter-btn {
    padding: 6px 16px;
    border-radius: 20px;
    border: 1px solid var(--border);
    background: transparent;
    color: var(--text-light);
    font-size: 0.85rem;
    cursor: pointer;
    transition: var(--transition);
    font-family: var(--font-main);
}

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

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

.filter-btn.lecture.active {
    background: var(--lecture-badge);
    border-color: var(--lecture-badge);
}

.filter-btn.tutorial.active {
    background: var(--tutorial-badge);
    border-color: var(--tutorial-badge);
}

/* ===== Session Grid ===== */
.sessions-section {
    max-width: 1400px;
    margin: 0 auto;
    padding: 32px 2rem;
}

.section-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    margin-bottom: 24px;
}

.section-header h2 {
    font-size: 1.5rem;
    font-weight: 700;
}

.section-count {
    color: var(--text-light);
    font-size: 0.9rem;
    background: var(--surface);
    padding: 6px 16px;
    border-radius: 20px;
    border: 1px solid var(--border);
}

.sessions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(280px, 1fr));
    gap: 20px;
}

/* ===== Session Card ===== */
.session-card {
    background: var(--surface);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    padding: 20px;
    transition: var(--transition);
    cursor: pointer;
    position: relative;
    overflow: hidden;
}

.session-card:hover {
    border-color: var(--primary);
    box-shadow: var(--shadow-hover);
    transform: translateY(-2px);
}

.session-card.hidden {
    display: none;
}

.session-card .card-top {
    display: flex;
    justify-content: space-between;
    align-items: flex-start;
    margin-bottom: 12px;
}

.session-number {
    font-size: 2rem;
    font-weight: 800;
    background: linear-gradient(135deg, var(--primary), var(--accent));
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    background-clip: text;
    line-height: 1;
}

.session-badge {
    padding: 4px 12px;
    border-radius: 12px;
    font-size: 0.75rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.session-badge.lecture {
    background: rgba(108, 92, 231, 0.15);
    color: var(--primary-light);
    border: 1px solid rgba(108, 92, 231, 0.3);
}

.session-badge.tutorial {
    background: rgba(0, 184, 148, 0.15);
    color: var(--accent);
    border: 1px solid rgba(0, 184, 148, 0.3);
}

.session-card .card-title {
    font-size: 1rem;
    font-weight: 600;
    margin-bottom: 8px;
    line-height: 1.4;
    color: var(--text);
}

.session-card .card-desc {
    font-size: 0.85rem;
    color: var(--text-light);
    margin-bottom: 12px;
    line-height: 1.5;
    display: -webkit-box;
    -webkit-line-clamp: 2;
    -webkit-box-orient: vertical;
    overflow: hidden;
}

.session-card .card-footer {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding-top: 12px;
    border-top: 1px solid var(--border);
}

.card-module {
    font-size: 0.8rem;
    color: var(--text-muted);
}

.card-link {
    font-size: 0.8rem;
    color: var(--primary-light);
    font-weight: 600;
}

.card-link:hover {
    color: var(--accent-light);
}

/* ===== Module Labels ===== */
.module-label {
    display: inline-block;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 0.7rem;
    font-weight: 600;
}

.module-I { background: rgba(108, 92, 231, 0.2); color: #a29bfe; }
.module-II { background: rgba(0, 206, 201, 0.2); color: #81ecec; }
.module-III { background: rgba(253, 203, 110, 0.2); color: #fdcb6e; }
.module-IV { background: rgba(225, 112, 85, 0.2); color: #e17055; }
.module-V { background: rgba(0, 184, 148, 0.2); color: #00b894; }

/* ===== No Results ===== */
.no-results {
    grid-column: 1 / -1;
    text-align: center;
    padding: 60px 2rem;
    color: var(--text-muted);
}

.no-results .icon {
    font-size: 3rem;
    margin-bottom: 16px;
}

.no-results h3 {
    font-size: 1.2rem;
    margin-bottom: 8px;
    color: var(--text-light);
}

/* ===== Footer ===== */
.site-footer {
    background: var(--surface);
    border-top: 1px solid var(--border);
    padding: 32px 2rem;
    margin-top: 60px;
}

.footer-inner {
    max-width: 1400px;
    margin: 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    flex-wrap: wrap;
    gap: 16px;
}

.footer-copy {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.footer-links {
    display: flex;
    gap: 20px;
}

.footer-links a {
    color: var(--text-muted);
    font-size: 0.85rem;
}

.footer-links a:hover {
    color: var(--primary-light);
}

/* ===== Loading ===== */
.loading {
    grid-column: 1 / -1;
    text-align: center;
    padding: 60px;
    color: var(--text-light);
}

.spinner {
    width: 40px;
    height: 40px;
    border: 3px solid var(--border);
    border-top-color: var(--primary);
    border-radius: 50%;
    animation: spin 0.8s linear infinite;
    margin: 0 auto 16px;
}

@keyframes spin {
    to { transform: rotate(360deg); }
}

/* ===== Chapter Container ===== */
.chapter-container {
    max-width: 900px;
    margin: 0 auto;
    padding: 2rem;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
    .hero h1 {
        font-size: 1.8rem;
    }
    .hero-subtitle {
        font-size: 1rem;
    }
    .hero-meta {
        gap: 16px;
    }
    .sessions-grid {
        grid-template-columns: 1fr;
    }
    .filter-inner {
        flex-direction: column;
        align-items: stretch;
    }
    .filter-group {
        justify-content: center;
    }
    .header-inner {
        flex-direction: column;
        height: auto;
        padding: 12px 0;
    }
    .main-nav {
        gap: 12px;
        flex-wrap: wrap;
        justify-content: center;
    }
    .site-header {
        padding: 0 1rem;
    }
    .stats-inner {
        gap: 12px;
    }
    .stat-item {
        padding: 6px 16px;
    }
    .stat-number {
        font-size: 1.3rem;
    }
}

@media (max-width: 480px) {
    .hero { padding: 40px 1rem; }
    .hero h1 { font-size: 1.4rem; }
    .session-number { font-size: 1.5rem; }
    .sessions-section { padding: 20px 1rem; }
    .section-header { flex-direction: column; gap: 8px; }
}