@import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;500;600;700&family=JetBrains+Mono:wght@400;700;800&display=swap');

/* ── Design Tokens ─────────────────────────────────────── */
:root {
  --bg:          #F8F9FA;
  --surface:     #FFFFFF;
  --ink:         #111827;
  --ink-soft:    #6B7280;
  --ink-muted:   #9CA3AF;
  --accent:      #2563EB;
  --accent-lt:   #EFF6FF;
  --border:      #E5E7EB;
  --border-md:   #D1D5DB;

  --ap:          #7C3AED;
  --ap-lt:       #F5F3FF;
  --cie:         #059669;
  --cie-lt:      #ECFDF5;
  --igcse:       #D97706;
  --igcse-lt:    #FFFBEB;

  --code-bg:     #0F172A;
  --code-text:   #E2E8F0;

  --font-display: "JetBrains Mono", "Fira Code", monospace;
  --font-body:    "Inter", system-ui, sans-serif;
  --font-mono:    "JetBrains Mono", "Fira Code", monospace;

  --nav-h:    64px;
  --max-w:    1100px;
  --r:        10px;
  --r-sm:     6px;
  --shadow:   0 1px 3px rgba(0,0,0,.07), 0 4px 12px rgba(0,0,0,.06);
  --shadow-lg:0 8px 32px rgba(0,0,0,.12);
  --ease:     0.18s ease;
}

/* ── Reset ─────────────────────────────────────────────── */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.65;
  color: var(--ink);
  background: var(--bg);
  padding-top: var(--nav-h);
}
img  { max-width: 100%; display: block; }
a    { color: var(--accent); text-decoration: none; transition: color var(--ease); }
a:hover { color: #1d4ed8; }
ul, ol { list-style: none; }
button { cursor: pointer; font-family: inherit; border: none; background: none; }

/* ── Typography ────────────────────────────────────────── */
h1,h2,h3,h4 { line-height: 1.25; font-weight: 700; }
h1 { font-size: 2.25rem; }
h2 { font-size: 1.6rem; }
h3 { font-size: 1.1rem; }
p  { margin-bottom: .75rem; }
p:last-child { margin-bottom: 0; }
code { font-family: var(--font-mono); font-size: .85em;
       background: #F1F5F9; padding: 2px 6px; border-radius: 4px; }
pre  { font-family: var(--font-mono); font-size: .875rem;
       background: var(--code-bg); color: var(--code-text);
       padding: 20px 24px; border-radius: var(--r);
       overflow-x: auto; line-height: 1.75; }
pre code { background: none; padding: 0; font-size: inherit; }

/* ── Layout ────────────────────────────────────────────── */
.container  { max-width: var(--max-w); margin: 0 auto; padding: 0 24px; }
.section    { padding: 72px 0; }
.section-sm { padding: 48px 0; }
.grid-2 { display: grid; grid-template-columns: repeat(2,1fr); gap: 20px; }
.grid-3 { display: grid; grid-template-columns: repeat(3,1fr); gap: 20px; }
.flex-center { display: flex; align-items: center; justify-content: center; }
.text-muted  { color: var(--ink-soft); font-size: .875rem; }
.text-center { text-align: center; }
.mt-2 { margin-top: 8px; }
.mt-4 { margin-top: 16px; }
.mt-6 { margin-top: 24px; }
.gap-2 { gap: 8px; }
.gap-3 { gap: 12px; }

/* ── Page header ───────────────────────────────────────── */
.page-header {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 48px 0 40px;
}
.page-header h1 {
  font-family: var(--font-display);
  font-size: 2rem;
  font-weight: 800;
  letter-spacing: -.02em;
  margin-bottom: 8px;
}
.page-header p { color: var(--ink-soft); max-width: 560px; }

/* ── Section heading ───────────────────────────────────── */
.sec-title    { font-size: 1.4rem; font-weight: 700; margin-bottom: 6px; }
.sec-subtitle { color: var(--ink-soft); margin-bottom: 32px; font-size: .9rem; }

/* ── Footer ────────────────────────────────────────────── */
.site-footer {
  background: var(--ink);
  color: rgba(255,255,255,.7);
  padding: 48px 0 24px;
  margin-top: 80px;
}
.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr;
  gap: 40px;
  margin-bottom: 36px;
}
.footer-brand {
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 800;
  color: #fff;
  margin-bottom: 8px;
}
.site-footer h4    { color: #fff; font-size: .875rem; margin-bottom: 12px; font-weight: 600; }
.site-footer p,
.site-footer a     { color: rgba(255,255,255,.65); font-size: .8rem; }
.site-footer a:hover { color: #fff; }
.site-footer ul    { display: flex; flex-direction: column; gap: 8px; }
.footer-bottom {
  border-top: 1px solid rgba(255,255,255,.1);
  padding-top: 20px;
  font-size: .75rem;
  color: rgba(255,255,255,.4);
  text-align: center;
}