/* Design tokens ported from the Rsquared Academy site family
   (aravindhebbali.com / pkgs / ebooks) for a consistent cross-site look. */

@font-face {
  font-family: "Source Sans Pro";
  font-style: normal;
  font-weight: 400;
  font-display: swap;
  src: url("../fonts/source-sans-pro-latin-400.woff2") format("woff2");
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

@font-face {
  font-family: "Source Sans Pro";
  font-style: normal;
  font-weight: 600;
  font-display: swap;
  src: url("../fonts/source-sans-pro-latin-600.woff2") format("woff2");
  unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+0304, U+0308, U+0329, U+2000-206F, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD;
}

:root {
  color-scheme: light dark;

  --ink: #0f172a;
  --body: #334155;
  --muted: #64748b;
  --line: #e2e8f0;
  --line-soft: #f1f5f9;
  --line-strong: #cbd5e1;
  --accent: #2563eb;
  --accent-dk: #1d4ed8;
  --accent-ring: rgba(37, 99, 235, 0.28);
  --surface: #ffffff;
  --canvas: #fbfcfd;

  --note-bg: #f0f9ff;
  --note-line: #e0f2fe;
  --note-ink: #075985;

  --beg-bg: #dcfce7;
  --beg-ink: #166534;
  --int-bg: #fef9c3;
  --int-ink: #854d0e;
  --adv-bg: #fee2e2;
  --adv-ink: #991b1b;

  --on-accent: #ffffff;
  --on-ink: #ffffff;
  --ink-hover: #1e293b;
  --shadow-xs: rgba(2, 6, 23, 0.04);
  --shadow-sm: rgba(2, 6, 23, 0.08);
  --shadow-md: rgba(2, 6, 23, 0.12);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --surface: #0f172a;
    --canvas: #020617;
    --ink: #f8fafc;
    --body: #e2e8f0;
    --muted: #a8b6c8;
    --line: #24334a;
    --line-soft: #182338;
    --line-strong: #3d4d66;
    --accent: #7cc0ff;
    --accent-dk: #a8d3ff;
    --accent-ring: rgba(124, 192, 255, 0.34);
    --on-ink: #0f172a;
    --ink-hover: #e2e8f0;
    --note-bg: #0c2436;
    --note-ink: #8fdcff;
    --note-line: #123a52;
    --beg-bg: #053021;
    --beg-ink: #8ef0b0;
    --int-bg: #2c2609;
    --int-ink: #ffe14d;
    --adv-bg: #331318;
    --adv-ink: #ffb3b3;
    --shadow-xs: rgba(2, 6, 23, 0.30);
    --shadow-sm: rgba(2, 6, 23, 0.45);
    --shadow-md: rgba(2, 6, 23, 0.60);
    --on-accent: #0f172a;
  }
}

:root[data-theme="dark"] {
  --surface: #0f172a;
  --canvas: #020617;
  --ink: #f8fafc;
  --body: #e2e8f0;
  --muted: #a8b6c8;
  --line: #24334a;
  --line-soft: #182338;
  --line-strong: #3d4d66;
  --accent: #7cc0ff;
  --accent-dk: #a8d3ff;
  --accent-ring: rgba(124, 192, 255, 0.34);
  --on-ink: #0f172a;
  --ink-hover: #e2e8f0;
  --note-bg: #0c2436;
  --note-ink: #8fdcff;
  --note-line: #123a52;
  --beg-bg: #053021;
  --beg-ink: #8ef0b0;
  --int-bg: #2c2609;
  --int-ink: #ffe14d;
  --adv-bg: #331318;
  --adv-ink: #ffb3b3;
  --shadow-xs: rgba(2, 6, 23, 0.30);
  --shadow-sm: rgba(2, 6, 23, 0.45);
  --shadow-md: rgba(2, 6, 23, 0.60);
  --on-accent: #0f172a;
}

/* ---------- Base ---------- */

body {
  color: var(--body);
  background: var(--canvas);
  text-align: left;
  font-size: 1rem;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4, h5 {
  color: var(--ink);
  font-weight: 600;
  letter-spacing: -0.011em;
  text-align: left;
}

h1, h2, h3 {
  font-family: Georgia, "Times New Roman", serif;
  letter-spacing: -0.015em;
}

h1 { font-size: 2.25rem; font-weight: 700; line-height: 1.2; }
h2 { font-size: 1.5rem; margin-top: 3.5rem; margin-bottom: 1.25rem; padding-bottom: 0.6rem; border-bottom: 1px solid var(--line); }
h3 { font-size: 1.125rem; margin-top: 2rem; margin-bottom: 0.6rem; }

p { margin-bottom: 1.1rem; }

a {
  color: var(--accent);
  text-decoration: none;
  border-bottom: 1px solid var(--accent-ring);
}

a:hover { color: var(--accent-dk); border-bottom-color: var(--accent-dk); }

a:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
  border-bottom-color: transparent;
}

main p, main li { max-width: 68ch; }

main ul, main ol { padding-left: 1.25rem; }
main li { margin-bottom: 0.35rem; }

code {
  color: var(--ink);
  background: var(--line-soft);
  padding: 0.1em 0.35em;
  border-radius: 3px;
  font-size: 0.875em;
}

hr { border: 0; border-top: 1px solid var(--line); margin: 3rem 0; }