/* MindView Virtual Classroom — Global Styles */

:root {
    --primary: #2563eb;
    --primary-dark: #1d4ed8;
    --bg: #f8fafc;
    --card: #ffffff;
    --border: #e2e8f0;
    --text: #1e293b;
    --muted: #64748b;
    --strand-a: #059669;
    --strand-b: #dc2626;
    --strand-c: #2563eb;
    --strand-d: #7c3aed;
    --radius: 12px;
}

* { margin: 0; padding: 0; box-sizing: border-box; }
body { font-family: 'Segoe UI', system-ui, -apple-system, sans-serif; background: var(--bg); color: var(--text); line-height: 1.6; }
.container { max-width: 1100px; margin: 0 auto; padding: 0 24px; }
a { color: var(--primary); text-decoration: none; }
h2 { font-size: 36px; font-weight: 800; margin-bottom: 10px; }
.section-sub { color: var(--muted); font-size: 18px; margin-bottom: 32px; }

/* ===== NAVBAR ===== */
.navbar { background: #fff; border-bottom: 1px solid var(--border); padding: 10px 0; position: sticky; top: 0; z-index: 100; }
.nav-container { max-width: 1100px; margin: 0 auto; padding: 0 24px; display: flex; justify-content: space-between; align-items: center; }
.nav-brand { display: flex; align-items: center; }
.brand-logo { height: 52px; width: auto; display: block; }
.nav-links { display: flex; gap: 28px; }
.nav-links a { color: var(--muted); font-weight: 600; font-size: 17px; transition: color 0.2s; }
.nav-links a:hover, .nav-links a.active { color: var(--primary); }

/* ===== HERO ===== */
.hero { background: linear-gradient(135deg, #1e3a8a 0%, #2563eb 50%, #3b82f6 100%); color: #fff; padding: 90px 24px; text-align: center; }
.hero-content { max-width: 800px; margin: 0 auto; }
.hero-badge { display: inline-block; background: rgba(255,255,255,0.15); padding: 10px 24px; border-radius: 24px; font-size: 18px; font-weight: 600; margin-bottom: 28px; backdrop-filter: blur(4px); letter-spacing: 0.3px; }
.hero h1 { margin-bottom: 24px; line-height: 1; }
.hero-logo-wrap { display: inline-block; background: #fff; border-radius: 16px; padding: 14px 32px; box-shadow: 0 4px 20px rgba(0,0,0,0.15); }
.hero-logo { height: 90px; width: auto; display: block; }
.hero h2 { font-size: 42px; font-weight: 800; opacity: 1; margin-bottom: 16px; letter-spacing: -0.5px; }
.hero-sub { font-size: 22px; font-weight: 600; opacity: 0.9; margin-bottom: 40px; }
.hero-stats { display: flex; justify-content: center; gap: 56px; margin-bottom: 40px; }
.stat { text-align: center; }
.stat-num { display: block; font-size: 48px; font-weight: 900; }
.stat-label { font-size: 18px; font-weight: 600; opacity: 0.85; }
.hero-cta { display: inline-block; background: #fff; color: var(--primary); padding: 16px 40px; border-radius: 8px; font-weight: 800; font-size: 18px; transition: transform 0.2s, box-shadow 0.2s; }
.hero-cta:hover { transform: translateY(-2px); box-shadow: 0 8px 24px rgba(0,0,0,0.2); }

/* ===== COURSE INFO ===== */
.course-info { padding: 64px 0; }
.course-info p { color: var(--muted); font-size: 16px; max-width: 700px; margin-bottom: 32px; }
.info-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(280px, 1fr)); gap: 20px; }
.info-card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; }
.info-icon { font-size: 28px; margin-bottom: 12px; }
.info-card h3 { font-size: 16px; margin-bottom: 8px; }
.info-card p { font-size: 14px; color: var(--muted); margin: 0; }

/* ===== UNITS ===== */
.units-section { padding: 64px 0; background: #fff; }
.strand-group { margin-bottom: 40px; }
.strand-label { display: inline-block; padding: 6px 16px; border-radius: 20px; font-size: 14px; font-weight: 700; margin-bottom: 16px; }
.strand-a { background: #d1fae5; color: var(--strand-a); }
.strand-b { background: #fee2e2; color: var(--strand-b); }
.strand-c { background: #dbeafe; color: var(--strand-c); }
.strand-d { background: #ede9fe; color: var(--strand-d); }
.units-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 16px; }
.unit-card { display: flex; background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); overflow: hidden; transition: all 0.2s; color: var(--text); }
.unit-card:hover { border-color: var(--primary); box-shadow: 0 4px 16px rgba(37,99,235,0.1); transform: translateY(-2px); }
.unit-num { background: var(--primary); color: #fff; display: flex; align-items: center; justify-content: center; width: 56px; min-height: 100%; font-size: 24px; font-weight: 800; flex-shrink: 0; }
.unit-body { padding: 16px 20px; flex: 1; }
.unit-body h3 { font-size: 16px; margin-bottom: 6px; }
.unit-body p { font-size: 13px; color: var(--muted); margin-bottom: 8px; }
.unit-meta { display: flex; gap: 16px; font-size: 12px; color: var(--muted); }

/* ===== ASSESSMENTS ===== */
.assessments-section { padding: 64px 0; }
.assess-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(300px, 1fr)); gap: 24px; }
.assess-type { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 24px; }
.assess-icon { width: 48px; height: 48px; border-radius: 12px; display: flex; align-items: center; justify-content: center; font-size: 24px; margin-bottom: 12px; }
.assess-type h3 { font-size: 18px; margin-bottom: 8px; }
.assess-type p { font-size: 14px; color: var(--muted); margin-bottom: 16px; }
.assess-links { display: flex; flex-wrap: wrap; gap: 6px; }
.assess-links a { display: inline-block; padding: 4px 12px; background: #f1f5f9; border-radius: 6px; font-size: 13px; font-weight: 600; color: var(--text); transition: all 0.2s; }
.assess-links a:hover { background: var(--primary); color: #fff; }

/* ===== TOOLS ===== */
.tools-section { padding: 64px 0; background: #fff; }
.tools-grid { display: grid; grid-template-columns: repeat(auto-fill, minmax(220px, 1fr)); gap: 16px; }
.tool-card { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 20px; text-align: center; transition: all 0.2s; color: var(--text); }
.tool-card:hover { border-color: var(--primary); box-shadow: 0 4px 12px rgba(0,0,0,0.06); }
.tool-icon { font-size: 32px; margin-bottom: 8px; }
.tool-card h3 { font-size: 15px; margin-bottom: 4px; }
.tool-card p { font-size: 13px; color: var(--muted); }

/* ===== FOOTER ===== */
.site-footer { background: #0f172a; color: #94a3b8; padding: 40px 0; text-align: center; font-size: 14px; }

/* ===== CHAPTER PAGE ===== */
.chapter-hero { padding: 48px 24px; color: #fff; }
.chapter-hero h1 { font-size: 32px; margin-bottom: 8px; }
.chapter-hero .strand-tag { display: inline-block; background: rgba(255,255,255,0.2); padding: 4px 12px; border-radius: 20px; font-size: 13px; margin-bottom: 12px; }
.chapter-hero p { opacity: 0.85; max-width: 600px; }

.topic-section { padding: 32px 0; border-bottom: 1px solid var(--border); }
.topic-header { display: flex; justify-content: space-between; align-items: center; margin-bottom: 16px; cursor: pointer; }
.topic-header h3 { font-size: 18px; }
.topic-header .toggle { font-size: 20px; color: var(--muted); transition: transform 0.3s; }

.video-list { list-style: none; }
.video-item { display: flex; align-items: center; gap: 12px; padding: 12px 16px; border: 1px solid var(--border); border-radius: 8px; margin-bottom: 8px; transition: all 0.2s; }
.video-item:hover { border-color: var(--primary); background: #f8fafc; }
.video-item .vid-icon { font-size: 20px; flex-shrink: 0; }
.video-item .vid-title { flex: 1; font-size: 14px; font-weight: 500; }
.video-item .vid-duration { font-size: 13px; color: var(--muted); }
.video-item .vid-type { font-size: 11px; padding: 2px 8px; border-radius: 10px; font-weight: 600; }
.vid-type.lecture { background: #dbeafe; color: #1e40af; }
.vid-type.homework { background: #fef3c7; color: #92400e; }
.vid-type.review { background: #d1fae5; color: #065f46; }

.expectations-box { background: #f1f5f9; border-radius: var(--radius); padding: 20px; margin: 24px 0; }
.expectations-box h3 { font-size: 16px; margin-bottom: 12px; }
.expectations-box ul { margin-left: 20px; }
.expectations-box li { font-size: 14px; color: var(--muted); margin-bottom: 6px; }

/* ===== RESPONSIVE ===== */
@media (max-width: 768px) {
    .hero-logo { height: 70px; }
    .hero h2 { font-size: 28px; }
    .hero-badge { font-size: 14px; }
    .hero-sub { font-size: 17px; }
    .hero-stats { gap: 24px; }
    .stat-num { font-size: 32px; }
    .stat-label { font-size: 14px; }
    .brand-logo { height: 38px; }
    .units-grid { grid-template-columns: 1fr; }
    .nav-links { display: none; }
}