/* Shared styles for the hub (home) page and the Questions page only.
   The chapter notes keep their own original styles and never load this file. */

:root {
  --bg: #f6f6f2;
  --surface: #ffffff;
  --surface-2: #f0f0ea;
  --ink: #15171c;
  --ink-2: #3a3e48;
  --muted: #646a77;
  --line: #e2e2da;
  --line-2: #d2d2c8;
  --accent: #3730a3;
  --accent-ink: #ffffff;
  --accent-soft: #ecebfb;
  --code-bg: #14161c;
  --code-ink: #e6e8ee;
  --good: #047857;
  --good-soft: #e3f4ec;
  --star: #b45309;
  --star-soft: #fdf1dc;
  --u1: #0e7490; --u2: #2563eb; --u3: #7c3aed; --u4: #059669; --u5: #d97706; --uq: #3730a3;
  --shadow: 0 1px 2px rgba(20, 20, 10, .05), 0 4px 16px rgba(20, 20, 10, .05);
  --radius: 14px;
  --f-head: "Bricolage Grotesque", system-ui, sans-serif;
  --f-body: "Atkinson Hyperlegible", system-ui, sans-serif;
  --f-mono: "JetBrains Mono", ui-monospace, Consolas, monospace;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f1115; --surface: #171a21; --surface-2: #1d212a; --ink: #eceef2; --ink-2: #c9cdd6;
    --muted: #9aa1ad; --line: #262a33; --line-2: #343945; --accent: #a5b4fc; --accent-ink: #12142a;
    --accent-soft: #23264a; --code-bg: #0b0c10; --good: #34d399; --good-soft: #12302a;
    --star: #fbbf24; --star-soft: #3a2c10;
    --u1: #22d3ee; --u2: #60a5fa; --u3: #a78bfa; --u4: #34d399; --u5: #fbbf24; --uq: #a5b4fc;
    --shadow: 0 1px 2px rgba(0, 0, 0, .3); color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0f1115; --surface: #171a21; --surface-2: #1d212a; --ink: #eceef2; --ink-2: #c9cdd6;
  --muted: #9aa1ad; --line: #262a33; --line-2: #343945; --accent: #a5b4fc; --accent-ink: #12142a;
  --accent-soft: #23264a; --code-bg: #0b0c10; --good: #34d399; --good-soft: #12302a;
  --star: #fbbf24; --star-soft: #3a2c10;
  --u1: #22d3ee; --u2: #60a5fa; --u3: #a78bfa; --u4: #34d399; --u5: #fbbf24; --uq: #a5b4fc;
  --shadow: 0 1px 2px rgba(0, 0, 0, .3); color-scheme: dark;
}

*, *::before, *::after { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; scroll-padding-top: 76px; }
body {
  margin: 0; background: var(--bg); color: var(--ink);
  font: 17px/1.6 var(--f-body);
}
a { color: inherit; }
img, svg { max-width: 100%; }
h1, h2, h3 { font-family: var(--f-head); line-height: 1.12; margin: 0; letter-spacing: -.015em; }
code { font-family: var(--f-mono); font-size: .88em; background: var(--surface-2); padding: .08em .36em; border-radius: 5px; }
.wrap { max-width: 1180px; margin: 0 auto; padding: 0 24px; }
.mono { font-family: var(--f-mono); }
code, pre, kbd { font-variant-ligatures: none; font-feature-settings: "liga" 0, "calt" 0; }
.eyebrow { font: 600 12.5px/1.4 var(--f-mono); letter-spacing: .08em; text-transform: uppercase; color: var(--muted); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

/* ---------- Top bar ---------- */
.top {
  position: sticky; top: 0; z-index: 20; background: color-mix(in srgb, var(--bg) 88%, transparent);
  backdrop-filter: saturate(1.4) blur(10px); -webkit-backdrop-filter: saturate(1.4) blur(10px);
  border-bottom: 1px solid var(--line);
}
.top .wrap { display: flex; align-items: center; gap: 16px; height: 60px; }
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; font: 800 18px/1 var(--f-head); }
.brand-mark { width: 30px; height: 30px; flex: none; }
.top nav { margin-left: auto; display: flex; gap: 4px; }
.top nav a {
  text-decoration: none; font-weight: 700; font-size: 14.5px; color: var(--ink-2);
  padding: 8px 12px; border-radius: 9px;
}
.top nav a:hover { background: var(--surface-2); color: var(--ink); }
.top nav a[aria-current="page"] { background: var(--accent-soft); color: var(--accent); }
.theme-btn {
  width: 38px; height: 38px; border-radius: 10px; border: 1px solid var(--line); background: var(--surface);
  color: var(--ink-2); display: grid; place-items: center; cursor: pointer; flex: none;
}
.theme-btn:hover { color: var(--ink); border-color: var(--line-2); }
.theme-btn svg { width: 18px; height: 18px; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: 8px; height: 46px; padding: 0 20px; border-radius: 12px;
  font: 700 15.5px/1 var(--f-body); text-decoration: none; border: 1px solid transparent; cursor: pointer;
}
.btn-primary { background: var(--ink); color: var(--bg); }
.btn-primary:hover { opacity: .9; }
.btn-ghost { background: var(--surface); border-color: var(--line-2); color: var(--ink); }
.btn-ghost:hover { border-color: var(--ink-2); }

/* ---------- Footer ---------- */
.foot { border-top: 1px solid var(--line); margin-top: 80px; padding: 28px 0 40px; color: var(--muted); font-size: 14.5px; }
.foot .wrap { display: flex; flex-wrap: wrap; gap: 8px 24px; justify-content: space-between; }

@media (max-width: 720px) {
  body { font-size: 16px; }
  .wrap { padding: 0 16px; }
  .top nav a.hide-sm { display: none; }
  .top nav a { padding: 8px 9px; font-size: 14px; }
  .brand span { display: none; }
}
@media print {
  .top, .theme-btn, .foot { display: none !important; }
  body { background: #fff; color: #000; }
}