/* ===== Summaries Shared Styles ===== */
* { box-sizing: border-box; margin: 0; padding: 0; }

:root {
    --deep-petrol: #003B46;
    --muted-teal: #00606B;
    --dusty-aqua: #2F8592;
    --frost-white: #E8F1F2;
    --gold: #D4AF37;

    /* Theme Bridge */
    --deep-petrol: var(--t-deep-petrol);
    --muted-teal: var(--t-muted-teal);
    --dusty-aqua: var(--t-dusty-aqua);
    --frost-white: var(--t-frost-white);
    --gold: var(--t-gold);

    /* Readable text palette */
    --text-body: #3d4f5f;
    --text-heading: var(--deep-petrol);
    --text-muted: #6b7b8d;
}

/* ===== INDEX PAGE ===== */

body.index-page {
    font-family: 'Heebo', system-ui, sans-serif;
    background: var(--frost-white);
    color: var(--text-body);
    min-height: 100vh;
    line-height: 1.7;
}

/* ===== LESSON PAGE ===== */

body.lesson-page {
    font-family: 'Heebo', system-ui, sans-serif;
    background: #fff;
    color: var(--text-body);
    line-height: 1.8;
    font-size: 16px;
}

/* ===== SHARED: Hero ===== */

.hero {
    background: linear-gradient(135deg, var(--deep-petrol) 0%, var(--muted-teal) 100%);
    text-align: center;
    position: relative;
}

.hero::after {
    content: '';
    position: absolute;
    bottom: -30px;
    left: 0;
    right: 0;
    height: 60px;
    border-radius: 50% 50% 0 0 / 100% 100% 0 0;
}

body.index-page .hero { padding: 60px 20px 80px; }
body.index-page .hero::after { background: var(--frost-white); }
body.lesson-page .hero { padding: 50px 20px 70px; }
body.lesson-page .hero::after { background: #fff; }

.hero h1 {
    font-size: 32px;
    font-weight: 900;
    color: #ffffff;
    margin-bottom: 10px;
    letter-spacing: -0.02em;
}

body.index-page .hero h1 { font-size: 36px; margin-bottom: 12px; }

.hero p,
.hero-sub {
    font-size: 17px;
    color: var(--gold);
    font-weight: 300;
}

body.index-page .hero p {
    color: var(--frost-white);
    opacity: 0.9;
    font-size: 18px;
}

/* ===== INDEX: Badge & Back Link ===== */

.hero-badge {
    display: inline-block;
    background: var(--gold);
    color: var(--deep-petrol);
    font-weight: 800;
    font-size: 14px;
    padding: 6px 20px;
    border-radius: 20px;
    margin-bottom: 20px;
}

.back-link {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    color: var(--frost-white);
    text-decoration: none;
    font-size: 14px;
    position: absolute;
    top: 20px;
    right: 20px;
    opacity: 0.8;
    transition: opacity 0.3s;
}

.back-link:hover { opacity: 1; }

/* ===== INDEX: Cards Grid ===== */

.container {
    max-width: 900px;
    margin: -10px auto 60px;
    padding: 0 20px;
    position: relative;
    z-index: 1;
}

.cards { display: grid; gap: 20px; }

.card {
    background: white;
    border-radius: 16px;
    overflow: hidden;
    box-shadow: 0 4px 20px rgba(0, 59, 70, 0.08);
    transition: transform 0.3s, box-shadow 0.3s;
    text-decoration: none;
    color: inherit;
    display: grid;
    grid-template-columns: 100px 1fr;
}

.card:hover {
    transform: translateY(-4px);
    box-shadow: 0 8px 30px rgba(0, 59, 70, 0.15);
}

.card-number {
    background: linear-gradient(135deg, var(--deep-petrol), var(--muted-teal));
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    color: #ffffff;
    padding: 20px;
}

.card-number span { font-size: 42px; font-weight: 900; line-height: 1; color: #ffffff; }
.card-number small { font-size: 12px; color: #D4AF37; font-weight: 600; margin-top: 4px; }

.card-body { padding: 24px; }

.card-title {
    font-size: 20px;
    font-weight: 700;
    color: var(--text-heading);
    margin-bottom: 8px;
}

.card-topics { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 12px; }

.card-topic {
    background: var(--frost-white);
    color: var(--dusty-aqua);
    font-size: 12px;
    font-weight: 600;
    padding: 4px 12px;
    border-radius: 12px;
}

.card-meta { display: flex; gap: 16px; font-size: 13px; color: var(--text-muted); }
.card-meta span { display: flex; align-items: center; gap: 4px; }

/* ===== LESSON: Nav Links ===== */

.nav-links {
    display: flex;
    justify-content: space-between;
    max-width: 800px;
    margin: 0 auto 30px;
}

.nav-links a {
    color: var(--frost-white);
    text-decoration: none;
    font-size: 14px;
    opacity: 0.8;
    transition: opacity 0.3s;
}

.nav-links a:hover { opacity: 1; }

.lesson-badge {
    display: inline-block;
    background: var(--gold);
    color: var(--deep-petrol);
    font-weight: 900;
    font-size: 28px;
    width: 64px;
    height: 64px;
    line-height: 64px;
    border-radius: 50%;
    margin-bottom: 16px;
}

/* ===== LESSON: Content ===== */

.content {
    max-width: 800px;
    margin: 0 auto;
    padding: 10px 24px 60px;
}

/* Section */
.section { margin-bottom: 36px; }

.section-header {
    display: flex;
    align-items: center;
    gap: 12px;
    margin-bottom: 18px;
    padding-bottom: 12px;
    border-bottom: 2px solid var(--gold);
}

.section-icon {
    width: 40px;
    height: 40px;
    background: linear-gradient(135deg, var(--deep-petrol), var(--muted-teal));
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: #ffffff;
    font-size: 18px;
    flex-shrink: 0;
}

.section-title {
    font-size: 22px;
    font-weight: 700;
    color: var(--text-heading);
}

/* Topic blocks */
.topic {
    background: var(--frost-white);
    border-radius: 12px;
    padding: 22px 26px;
    margin-bottom: 16px;
    border-right: 4px solid var(--dusty-aqua);
}

.topic-title {
    font-size: 17px;
    font-weight: 700;
    color: var(--muted-teal);
    margin-bottom: 12px;
}

.topic ul { list-style: none; padding: 0; }

.topic li {
    padding: 5px 0;
    padding-right: 22px;
    position: relative;
    line-height: 1.8;
}

.topic li::before {
    content: '';
    position: absolute;
    right: 0;
    top: 13px;
    width: 8px;
    height: 8px;
    background: var(--gold);
    border-radius: 50%;
}

.topic p { margin: 10px 0; line-height: 1.8; }

/* Highlight box */
.highlight-box {
    background: linear-gradient(135deg, var(--deep-petrol), var(--muted-teal));
    color: #ffffff;
    border-radius: 12px;
    padding: 26px;
    margin-bottom: 16px;
}

.highlight-box p,
.highlight-box span {
    color: #ffffff;
}

.highlight-box .box-title {
    color: #D4AF37;
    font-weight: 700;
    font-size: 17px;
    margin-bottom: 14px;
}

.highlight-box ul { list-style: none; padding: 0; }

.highlight-box li {
    padding: 7px 0;
    padding-right: 24px;
    position: relative;
    color: #ffffff;
    line-height: 1.8;
}

.highlight-box li::before {
    content: '';
    position: absolute;
    right: 0;
    top: 16px;
    width: 10px;
    height: 2px;
    background: var(--gold);
}

/* Numbered list */
.numbered-list {
    counter-reset: item;
    list-style: none;
    padding: 0;
}

.numbered-list li {
    counter-increment: item;
    padding: 12px 0 12px 0;
    padding-right: 44px;
    position: relative;
    border-bottom: 1px solid rgba(0, 59, 70, 0.08);
    line-height: 1.8;
}

.numbered-list li::before {
    content: counter(item);
    position: absolute;
    right: 0;
    top: 12px;
    width: 28px;
    height: 28px;
    background: var(--gold);
    color: var(--deep-petrol);
    border-radius: 50%;
    font-weight: 700;
    font-size: 14px;
    display: flex;
    align-items: center;
    justify-content: center;
}

.numbered-list li:last-child { border-bottom: none; }

/* Key principle */
.principle {
    display: flex;
    gap: 12px;
    align-items: flex-start;
    background: white;
    border: 2px solid var(--gold);
    border-radius: 12px;
    padding: 18px 22px;
    margin-bottom: 12px;
}

.principle-icon { color: var(--gold); font-size: 20px; flex-shrink: 0; margin-top: 2px; }
.principle-text { font-weight: 600; color: var(--text-heading); line-height: 1.7; }

/* Homework */
.homework {
    background: var(--frost-white);
    border-radius: 16px;
    padding: 26px;
    border: 2px dashed var(--dusty-aqua);
}

.homework-item {
    padding: 12px 0;
    padding-right: 34px;
    position: relative;
    border-bottom: 1px solid rgba(0, 59, 70, 0.08);
}

.homework-item:last-child { border-bottom: none; }

.homework-item::before {
    content: '\1F381';
    position: absolute;
    right: 0;
    top: 12px;
    font-size: 18px;
}

.homework-note { font-size: 14px; color: var(--text-muted); margin-top: 6px; line-height: 1.7; }

/* Reference bar */
.ref-bar {
    display: flex;
    gap: 20px;
    background: var(--deep-petrol);
    color: #ffffff;
    border-radius: 12px;
    padding: 18px 26px;
    margin-top: 36px;
}

.ref-bar span { display: flex; align-items: center; gap: 8px; font-size: 15px; color: #ffffff; }
.ref-bar .ref-icon { color: #D4AF37; }

/* Bottom nav */
.bottom-nav {
    display: flex;
    justify-content: space-between;
    max-width: 800px;
    margin: 30px auto;
    padding: 0 24px;
}

.bottom-nav a {
    display: inline-flex;
    align-items: center;
    gap: 8px;
    background: var(--frost-white);
    color: var(--text-heading);
    text-decoration: none;
    padding: 12px 24px;
    border-radius: 10px;
    font-weight: 600;
    transition: background 0.3s;
}

.bottom-nav a:hover { background: var(--gold); color: var(--deep-petrol); }

/* ===== SHARED: Footer ===== */

.footer {
    text-align: center;
    padding: 30px 20px;
    color: var(--text-muted);
    font-size: 14px;
    border-top: 1px solid rgba(0, 59, 70, 0.1);
}

.footer a { color: var(--gold); text-decoration: none; font-weight: 600; }

/* ===== Print ===== */

@media print {
    .hero { padding: 30px 20px 40px; -webkit-print-color-adjust: exact; print-color-adjust: exact; }
    .hero::after { display: none; }
    .hero h1 { color: #ffffff !important; }
    .content { padding-top: 20px; }
    .bottom-nav, .nav-links, .back-link { display: none; }
    body { font-size: 14px; color: #333; }
    .section { break-inside: avoid; }
    .topic, .highlight-box, .principle, .homework { break-inside: avoid; }
    .highlight-box, .highlight-box p, .highlight-box li, .highlight-box span { color: #ffffff !important; }
    .highlight-box .box-title { color: #D4AF37 !important; }
    .ref-bar, .ref-bar span { color: #ffffff !important; }
    .card-number, .card-number span { color: #ffffff !important; }
}

/* ===== Mobile ===== */

@media (max-width: 600px) {
    .hero h1 { font-size: 26px; }
    body.index-page .hero h1 { font-size: 28px; }
    .section-title { font-size: 19px; }
    .card { grid-template-columns: 80px 1fr; }
    .card-number span { font-size: 32px; }
    .card-body { padding: 16px; }
    .card-title { font-size: 17px; }
    .ref-bar { flex-direction: column; gap: 8px; }
    .content { padding: 10px 16px 40px; }
    .topic { padding: 18px 20px; }
}

/* ===== Dark Mode ===== */

[data-theme="dark"] body {
    background: var(--t-bg) !important;
    color: var(--t-text) !important;
}

[data-theme="dark"] .container,
[data-theme="dark"] .card,
[data-theme="dark"] .content-section,
[data-theme="dark"] .lesson-card,
[data-theme="dark"] .summary-card,
[data-theme="dark"] .topic,
[data-theme="dark"] .principle,
[data-theme="dark"] .homework {
    background: var(--t-bg-card) !important;
    color: var(--t-text) !important;
    border-color: var(--t-border) !important;
}

[data-theme="dark"] h1,
[data-theme="dark"] h2,
[data-theme="dark"] h3,
[data-theme="dark"] .section-title,
[data-theme="dark"] .card-title,
[data-theme="dark"] .principle-text {
    color: var(--t-text) !important;
}

[data-theme="dark"] a { color: var(--t-gold) !important; }

[data-theme="dark"] .hero {
    background: linear-gradient(135deg, var(--t-deep-petrol) 0%, var(--t-muted-teal) 100%) !important;
}

[data-theme="dark"] .hero::after {
    background: var(--t-bg) !important;
}