/* ============================================================
   Garden Paper Mart Academy — Shared Stylesheet
   Cambridge A Level Mathematics (9709)
   Version 1.0 — 2026
   Primary:    Dark Red     #b71c1c
   Accent:     Silver/Steel #90a4ae
   Mid tone:   Red          #c62828
   Light bg:   Rose tint    #fff5f5
   Dark bg:    Deep Red     #7f0000
   ============================================================ */

/* ── RESET & BASE ───────────────────────────────────────────── */
* { box-sizing: border-box; margin: 0; padding: 0; }

body {
    font-family: Georgia, 'Times New Roman', serif;
    background: #fff8f8;
    color: #1a1a1a;
    line-height: 1.8;
}

/* ── HEADER ─────────────────────────────────────────────────── */
header {
    background: linear-gradient(135deg, #7f0000 0%, #b71c1c 60%, #c62828 100%);
    color: white;
    padding: 24px 30px;
    border-bottom: 4px solid #90a4ae;
}
.breadcrumb { font-size: 13px; margin-bottom: 8px; }
.breadcrumb a { color: #ffcdd2; text-decoration: none; }
.breadcrumb a:hover { text-decoration: underline; color: white; }
header h1 { font-size: 27px; font-weight: bold; letter-spacing: 0.5px; }
header p.subtitle {
    color: #ef9a9a;
    font-size: 14px;
    margin-top: 6px;
}

/* ── MAIN CONTAINER ─────────────────────────────────────────── */
.container { max-width: 900px; margin: 30px auto; padding: 0 20px 60px; }

/* ── SECTIONS ───────────────────────────────────────────────── */
section {
    background: white;
    border-radius: 8px;
    padding: 24px 28px;
    margin-bottom: 24px;
    box-shadow: 0 1px 5px rgba(183,28,28,0.08);
    border-top: 3px solid #b71c1c;
}

/* ── HEADINGS ───────────────────────────────────────────────── */
h2 {
    color: #b71c1c;
    font-size: 20px;
    margin-bottom: 14px;
    border-bottom: 2px solid #ffcdd2;
    padding-bottom: 8px;
}
h3 { color: #c62828; font-size: 17px; margin: 18px 0 10px; }
h4 { color: #b71c1c; margin-bottom: 6px; }

/* ── TYPOGRAPHY ─────────────────────────────────────────────── */
p  { margin-bottom: 12px; }
ul, ol { margin: 10px 0 12px 22px; }
li { margin-bottom: 6px; }
strong { color: #b71c1c; }

/* ── TABLES ─────────────────────────────────────────────────── */
table {
    width: 100%;
    border-collapse: collapse;
    margin-top: 14px;
    font-size: 15px;
}
th {
    background: #b71c1c;
    color: white;
    padding: 10px 14px;
    text-align: left;
    border: 1px solid #c62828;
}
td {
    padding: 10px 14px;
    border: 1px solid #ffcdd2;
    vertical-align: top;
}
tr:nth-child(even) td { background: #fff5f5; }

/* ── KEY CONCEPT BOX ────────────────────────────────────────── */
.key-concept {
    background: #fff5f5;
    padding: 13px 17px;
    border-left: 5px solid #b71c1c;
    margin: 14px 0;
    border-radius: 0 6px 6px 0;
    font-size: 15px;
}
.key-concept strong { color: #b71c1c; }

/* ── FORMULA / THEOREM BOX ──────────────────────────────────── */
.formula-box {
    background: #fff5f5;
    border: 2px solid #c62828;
    border-radius: 8px;
    padding: 16px 22px;
    margin: 14px 0;
}
.formula-box h4 {
    color: #b71c1c;
    margin-bottom: 10px;
    font-size: 15px;
    border-bottom: 1px solid #ffcdd2;
    padding-bottom: 6px;
}
.formula-box .formula {
    font-size: 16px;
    font-weight: bold;
    color: #7f0000;
    font-family: 'Times New Roman', Georgia, serif;
    margin: 8px 0;
    background: #ffebee;
    padding: 8px 14px;
    border-radius: 4px;
    display: block;
    border-left: 3px solid #b71c1c;
}

/* ── PROOF BOX ──────────────────────────────────────────────── */
.proof-box {
    background: #fce4ec;
    border: 1px solid #f48fb1;
    border-left: 5px solid #880e4f;
    border-radius: 0 8px 8px 0;
    padding: 16px 20px;
    margin: 14px 0;
}
.proof-box h4 { color: #880e4f; margin-bottom: 10px; font-size: 15px; }

/* ── SILVER / STEEL RULE BOX ────────────────────────────────── */
.rule-box {
    background: #eceff1;
    padding: 13px 17px;
    border-left: 5px solid #90a4ae;
    margin: 14px 0;
    border-radius: 0 6px 6px 0;
    font-size: 14px;
}
.rule-box strong { color: #37474f; }

/* ── WORKED EXAMPLE BOX ─────────────────────────────────────── */
.worked-example {
    background: #fff8f8;
    border: 1px solid #ef9a9a;
    border-radius: 8px;
    padding: 16px 20px;
    margin: 16px 0;
}
.worked-example h4 {
    color: #c62828;
    font-size: 15px;
    margin-bottom: 10px;
    border-bottom: 1px solid #ffcdd2;
    padding-bottom: 6px;
}
.worked-example .step {
    display: flex;
    gap: 12px;
    margin-bottom: 10px;
    font-size: 14px;
    align-items: flex-start;
}
.step-num {
    background: #b71c1c;
    color: white;
    border-radius: 50%;
    width: 24px;
    height: 24px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 12px;
    font-weight: bold;
    flex-shrink: 0;
    margin-top: 2px;
}
.step-content { flex: 1; line-height: 1.7; }
.step-content .math {
    font-family: 'Times New Roman', Georgia, serif;
    background: #ffebee;
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 15px;
    display: inline-block;
    margin: 2px 0;
    color: #7f0000;
}

/* ── TIP BOX ────────────────────────────────────────────────── */
.tip-box {
    background: #eceff1;
    padding: 13px 17px;
    border-left: 5px solid #90a4ae;
    margin: 14px 0;
    border-radius: 0 6px 6px 0;
    font-size: 14px;
}
.tip-box strong { color: #37474f; }

/* ── WARN BOX ───────────────────────────────────────────────── */
.warn-box {
    background: #fce4ec;
    padding: 13px 17px;
    border-left: 5px solid #880e4f;
    margin: 14px 0;
    border-radius: 0 6px 6px 0;
    font-size: 14px;
}
.warn-box strong { color: #880e4f; }

/* ── MEMORY BOX ─────────────────────────────────────────────── */
.memory-box {
    background: #e8eaf6;
    border: 1px solid #9fa8da;
    border-radius: 8px;
    padding: 14px 18px;
    margin: 14px 0;
    font-size: 14px;
}
.memory-box h4 { color: #283593; margin-bottom: 8px; font-size: 14px; }

/* ── CARD GOLD (important results) ─────────────────────────── */
.card-silver {
    background: #eceff1;
    border: 1px solid #b0bec5;
    border-radius: 6px;
    padding: 14px 16px;
}
.card-silver h4 { color: #37474f; margin-bottom: 6px; font-size: 15px; }

/* ── SYLLABUS REFERENCE BADGES ──────────────────────────────── */
.syllabus-ref {
    display: inline-block;
    background: #b71c1c;
    color: white;
    font-size: 11px;
    padding: 2px 10px;
    border-radius: 20px;
    margin-left: 8px;
    vertical-align: middle;
    font-weight: bold;
}
.syllabus-ref-silver {
    display: inline-block;
    background: #90a4ae;
    color: #1a1a1a;
    font-size: 11px;
    padding: 2px 10px;
    border-radius: 20px;
    margin-left: 8px;
    vertical-align: middle;
    font-weight: bold;
}

/* ── COMPONENT TAGS ─────────────────────────────────────────── */
.tag-pure1  { background: #ffebee; color: #b71c1c; border-radius: 12px; padding: 2px 10px; font-size: 11px; font-weight: bold; display: inline-block; }
.tag-pure2  { background: #fce4ec; color: #880e4f; border-radius: 12px; padding: 2px 10px; font-size: 11px; font-weight: bold; display: inline-block; }
.tag-pure3  { background: #f3e5f5; color: #4a148c; border-radius: 12px; padding: 2px 10px; font-size: 11px; font-weight: bold; display: inline-block; }
.tag-stats  { background: #e8f5e9; color: #1b5e20; border-radius: 12px; padding: 2px 10px; font-size: 11px; font-weight: bold; display: inline-block; }
.tag-mech   { background: #e3f2fd; color: #0d47a1; border-radius: 12px; padding: 2px 10px; font-size: 11px; font-weight: bold; display: inline-block; }
.tag-prob   { background: #fff9c4; color: #f57f17; border-radius: 12px; padding: 2px 10px; font-size: 11px; font-weight: bold; display: inline-block; }

/* ── PREREQUISITE BANNER ────────────────────────────────────── */
.prereq-banner {
    background: #fff8e1;
    border: 1px solid #ffe082;
    border-radius: 8px;
    padding: 14px 18px;
    margin-bottom: 20px;
    font-size: 14px;
    color: #5d4037;
}
.prereq-banner strong { color: #e65100; }

/* ── GRID LAYOUTS ───────────────────────────────────────────── */
.grid-2 {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 14px;
    margin-top: 14px;
}
.grid-3 {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr;
    gap: 14px;
    margin-top: 14px;
}

/* ── CARDS ──────────────────────────────────────────────────── */
.card {
    background: #fff5f5;
    border: 1px solid #ef9a9a;
    border-radius: 6px;
    padding: 14px 16px;
}
.card h4 { color: #b71c1c; margin-bottom: 6px; font-size: 15px; }

/* Dark card for exam technique */
.card-dark {
    background: #3e0000;
    border: 1px solid #b71c1c;
    border-radius: 6px;
    padding: 14px 16px;
    color: #ffcdd2;
}
.card-dark h4 { color: #90a4ae; margin-bottom: 6px; font-size: 15px; }
.card-dark p, .card-dark li { color: #ef9a9a; font-size: 13px; }

/* ── DIAGRAM BOX ────────────────────────────────────────────── */
.diagram-box {
    background: #fff8f8;
    border: 2px dashed #ef9a9a;
    border-radius: 8px;
    padding: 18px;
    text-align: center;
    margin: 14px 0;
}

/* ── PROGRESS BAR ───────────────────────────────────────────── */
.lesson-progress {
    background: white;
    border-radius: 8px;
    padding: 14px 20px;
    margin-bottom: 20px;
    box-shadow: 0 1px 5px rgba(183,28,28,0.08);
    display: flex;
    align-items: center;
    gap: 14px;
    flex-wrap: wrap;
    font-size: 13px;
    color: #555;
}
.progress-bar-wrap {
    flex: 1;
    background: #ffcdd2;
    border-radius: 20px;
    height: 8px;
    min-width: 120px;
}
.progress-bar-fill {
    background: linear-gradient(90deg, #b71c1c, #90a4ae);
    height: 8px;
    border-radius: 20px;
}

/* ── EXAM PRACTICE SECTION ──────────────────────────────────── */
.quiz-section {
    background: #fff5f5;
    padding: 24px 28px;
    border-radius: 8px;
    margin-bottom: 24px;
    border-top: 3px solid #90a4ae;
}
.quiz-section h3 { color: #b71c1c; margin-bottom: 14px; }

.q-block {
    background: white;
    border-radius: 6px;
    padding: 16px 20px;
    margin-bottom: 16px;
    border: 1px solid #ef9a9a;
}
.q-block p { margin-bottom: 6px; }

.answer {
    background: #eceff1;
    border-radius: 4px;
    padding: 10px 14px;
    margin-top: 10px;
    border-left: 3px solid #90a4ae;
    font-size: 14px;
}
.answer .math-ans {
    font-family: 'Times New Roman', Georgia, serif;
    background: #ffcdd2;
    padding: 2px 8px;
    border-radius: 4px;
    font-weight: bold;
    color: #7f0000;
    font-size: 15px;
}

.exam-tip {
    background: #fff8e1;
    border-radius: 4px;
    padding: 10px 14px;
    margin-top: 8px;
    border-left: 3px solid #f9a825;
    font-size: 13px;
}

/* ── NAVIGATION BUTTONS ─────────────────────────────────────── */
.lesson-nav {
    text-align: center;
    margin-top: 10px;
    display: flex;
    justify-content: center;
    gap: 16px;
    flex-wrap: wrap;
}
.btn {
    display: inline-block;
    background: #b71c1c;
    color: white;
    padding: 12px 28px;
    border-radius: 6px;
    text-decoration: none;
    font-size: 15px;
    transition: background 0.15s;
}
.btn:hover { background: #7f0000; }

.btn-silver {
    display: inline-block;
    background: #90a4ae;
    color: #1a1a1a;
    padding: 12px 28px;
    border-radius: 6px;
    text-decoration: none;
    font-size: 15px;
    font-weight: bold;
    transition: background 0.15s;
}
.btn-silver:hover { background: #78909c; color: white; }

.btn-outline {
    display: inline-block;
    background: white;
    color: #b71c1c;
    border: 2px solid #b71c1c;
    padding: 11px 28px;
    border-radius: 6px;
    text-decoration: none;
    font-size: 15px;
    transition: background 0.15s;
}
.btn-outline:hover { background: #fff5f5; }

/* ── FOOTER ─────────────────────────────────────────────────── */
footer {
    text-align: center;
    padding: 20px;
    color: #666;
    font-size: 13px;
    border-top: 1px solid #ffcdd2;
    background: white;
}

/* ── RESPONSIVE ─────────────────────────────────────────────── */
@media(max-width: 600px) {
    .grid-2, .grid-3 { grid-template-columns: 1fr; }
    header h1 { font-size: 20px; }
    .container { padding: 0 12px 40px; }
    .step { flex-direction: column; gap: 6px; }
}