@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700;800;900&family=Literata:ital,wght@0,400;0,700;1,400&display=swap');
* { margin: 0; padding: 0; box-sizing: border-box; }
:root {
    --bg: #FAFAF9; --text: #1C1917; --text-muted: #57534E;
    --border: #E7E5E4; --card: #FFFFFF;
    --accent: #2563EB; --accent-light: #EFF6FF; --accent-dark: #1E40AF;
    --tag-bg: #F3F4F6;
    --block1: #0EA5E9;
    --block2: #8B5CF6;
    --block3: #D97706;
    --block4: #059669;
    --bonus: #DC2626;
    --hw-bg: #FFF7ED;
    --hw-border: #F59E0B;
    --ex-bg: #ECFDF5;
    --ex-border: #059669;
    --empty-bg: #F5F5F4;
    --empty-text: #78716C;
}
html, body { overflow-x: hidden; }
body {
    font-family: 'Inter', -apple-system, sans-serif;
    background: var(--bg); color: var(--text);
    line-height: 1.6; font-size: 16px;
}

.topbar {
    padding: 14px 24px;
    border-bottom: 1px solid var(--border);
    background: var(--card);
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 16px;
}
.topbar a {
    color: var(--text-muted);
    text-decoration: none;
    font-size: 0.88rem;
    font-weight: 500;
}
.topbar a:hover { color: var(--accent); }
.topbar .breadcrumb { font-family: 'JetBrains Mono', ui-monospace, monospace; font-size: 0.82rem; }
.topbar .breadcrumb span { color: var(--text); font-weight: 600; }

.hero {
    padding: 64px 24px 40px;
    background: linear-gradient(180deg, #FFFFFF 0%, #FAFAF9 100%);
    border-bottom: 1px solid var(--border);
    text-align: center;
}
.hero .eyebrow {
    display: inline-block;
    font-size: 0.78rem;
    text-transform: uppercase;
    letter-spacing: 0.16em;
    color: var(--text-muted);
    background: var(--tag-bg);
    padding: 6px 14px;
    border-radius: 100px;
    margin-bottom: 20px;
}
.hero[data-block="1"] .eyebrow { background: rgba(14, 165, 233, 0.1); color: var(--block1); }
.hero[data-block="2"] .eyebrow { background: rgba(139, 92, 246, 0.1); color: var(--block2); }
.hero[data-block="3"] .eyebrow { background: rgba(217, 119, 6, 0.1); color: var(--block3); }
.hero[data-block="4"] .eyebrow { background: rgba(5, 150, 105, 0.1); color: var(--block4); }
.hero[data-block="B"] .eyebrow { background: rgba(220, 38, 38, 0.1); color: var(--bonus); }
.hero h1 {
    font-size: clamp(1.8rem, 4.5vw, 2.8rem);
    font-weight: 900;
    letter-spacing: -0.03em;
    line-height: 1.1;
    max-width: 860px;
    margin: 0 auto 12px;
}
.hero .subtitle {
    font-size: 1rem;
    color: var(--text-muted);
    max-width: 680px;
    margin: 0 auto;
    line-height: 1.55;
}
.hero .stats {
    display: flex;
    gap: 12px;
    justify-content: center;
    margin-top: 28px;
    flex-wrap: wrap;
}
.stat-chip {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 10px;
    padding: 10px 16px;
    font-size: 0.84rem;
}
.stat-chip strong {
    display: block;
    font-size: 1.3rem;
    font-weight: 800;
    color: var(--accent);
    line-height: 1;
    margin-bottom: 3px;
}
.stat-chip.hw strong { color: var(--hw-border); }
.stat-chip.ex strong { color: var(--ex-border); }

main { max-width: 920px; margin: 0 auto; padding: 48px 24px 96px; }

/* Block grid for index */
.block-grid {
    display: grid;
    grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
    gap: 18px;
    margin-top: 32px;
}
.block-card {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 24px;
    text-decoration: none;
    color: var(--text);
    transition: transform 0.2s, box-shadow 0.2s, border-color 0.2s;
    display: block;
    border-left-width: 4px;
}
.block-card[data-block="1"] { border-left-color: var(--block1); }
.block-card[data-block="2"] { border-left-color: var(--block2); }
.block-card[data-block="3"] { border-left-color: var(--block3); }
.block-card[data-block="4"] { border-left-color: var(--block4); }
.block-card[data-block="B"] { border-left-color: var(--bonus); }
.block-card:hover {
    transform: translateY(-3px);
    box-shadow: 0 12px 28px -10px rgba(0,0,0,0.18);
    border-color: var(--accent);
}
.block-card .tag {
    font-family: 'Literata', Georgia, serif;
    font-size: 1.6rem;
    font-style: italic;
    line-height: 1;
    font-weight: 700;
    margin-bottom: 6px;
}
.block-card[data-block="1"] .tag { color: var(--block1); }
.block-card[data-block="2"] .tag { color: var(--block2); }
.block-card[data-block="3"] .tag { color: var(--block3); }
.block-card[data-block="4"] .tag { color: var(--block4); }
.block-card[data-block="B"] .tag { color: var(--bonus); font-size: 1rem; }
.block-card h3 {
    font-size: 1.1rem;
    font-weight: 700;
    line-height: 1.3;
    margin-bottom: 8px;
    letter-spacing: -0.01em;
}
.block-card p {
    font-size: 0.85rem;
    color: var(--text-muted);
    line-height: 1.5;
}
.block-card .counts {
    display: flex;
    gap: 12px;
    margin-top: 14px;
    font-size: 0.78rem;
}
.block-card .count {
    display: inline-flex;
    align-items: center;
    gap: 4px;
    color: var(--text-muted);
}
.block-card .count strong {
    color: var(--text);
    font-weight: 700;
}

/* Lesson section for block pages */
.lesson-section {
    background: var(--card);
    border: 1px solid var(--border);
    border-radius: 14px;
    padding: 28px 32px;
    margin-bottom: 20px;
}
.lesson-section .lesson-head {
    display: flex;
    align-items: baseline;
    justify-content: space-between;
    gap: 16px;
    margin-bottom: 14px;
    flex-wrap: wrap;
}
.lesson-section .lesson-num {
    font-family: 'Literata', Georgia, serif;
    font-size: 0.85rem;
    font-style: italic;
    color: var(--text-muted);
    letter-spacing: 0.04em;
}
.lesson-section h2 {
    font-size: 1.3rem;
    font-weight: 800;
    letter-spacing: -0.02em;
    margin: 4px 0 0;
    flex: 1 1 auto;
    min-width: 200px;
}
.lesson-section .conspekt-link {
    color: var(--accent);
    text-decoration: none;
    font-size: 0.82rem;
    font-weight: 600;
    border: 1px solid var(--border);
    padding: 4px 12px;
    border-radius: 100px;
    background: var(--bg);
    transition: background 0.15s, border-color 0.15s;
    white-space: nowrap;
}
.lesson-section .conspekt-link:hover {
    background: var(--accent-light);
    border-color: var(--accent);
}

.hw-block, .ex-block {
    border-radius: 10px;
    padding: 18px 22px;
    margin-top: 14px;
}
.hw-block {
    background: var(--hw-bg);
    border: 1px solid var(--hw-border);
    border-left-width: 4px;
}
.hw-block .label {
    font-size: 0.74rem;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    color: var(--hw-border);
    font-weight: 700;
    margin-bottom: 8px;
}
.hw-block .label::before { content: "📋 "; }
.hw-block .content { font-size: 0.95rem; line-height: 1.6; color: var(--text); }
.hw-block .content p { margin: 8px 0; }
.hw-block .content ul { padding-left: 22px; margin: 8px 0; }
.hw-block .content li { margin: 6px 0; }
.hw-block .content em.quote {
    display: block;
    font-style: italic;
    color: var(--text-muted);
    border-left: 2px solid var(--hw-border);
    padding: 4px 0 4px 12px;
    margin: 10px 0 6px;
    font-size: 0.88rem;
    background: rgba(245, 158, 11, 0.05);
}

.ex-block {
    background: var(--ex-bg);
    border: 1px solid var(--ex-border);
    border-left-width: 4px;
}
.ex-block .label {
    font-size: 0.74rem;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    color: var(--ex-border);
    font-weight: 700;
    margin-bottom: 8px;
}
.ex-block .label::before { content: "🛠 "; }
.ex-block .content { font-size: 0.92rem; line-height: 1.55; color: var(--text); }
.ex-block .content ul { padding-left: 22px; margin: 4px 0; }
.ex-block .content li { margin: 6px 0; }

.empty-block {
    background: var(--empty-bg);
    border: 1px dashed var(--border);
    border-radius: 10px;
    padding: 12px 18px;
    margin-top: 14px;
    color: var(--empty-text);
    font-size: 0.88rem;
    font-style: italic;
}
.empty-block::before { content: "— "; }

footer {
    text-align: center;
    color: var(--text-muted);
    font-size: 0.82rem;
    padding: 32px 24px 60px;
    border-top: 1px solid var(--border);
}