/* Layout: single reading column under a slim brand bar; wide tables and formulas scroll inside their own frame */
:root {
  --bg: #e9edf1;
  --surface: #ffffff;
  --fg: #16202b;
  --muted: #5a6877;
  --line: #d3dae2;
  --accent: #1f5fbf;
  --accent-ink: #ffffff;
  --accent-soft: #dfe9f8;
  --font-display: "Archivo", "Helvetica Neue", Arial, sans-serif;
  --font-body: "Public Sans", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-data: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, monospace;
  --measure: 68ch;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0f141a; --surface: #171f28; --fg: #e4e9ee; --muted: #93a0ad; --line: #2a3542;
    --accent: #6aa2f0; --accent-ink: #0b1422; --accent-soft: #1c2b40;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0f141a; --surface: #171f28; --fg: #e4e9ee; --muted: #93a0ad; --line: #2a3542;
  --accent: #6aa2f0; --accent-ink: #0b1422; --accent-soft: #1c2b40;
  color-scheme: dark;
}
*, *::before, *::after { box-sizing: border-box; }
body { margin: 0; background: var(--bg); color: var(--fg); font: 17px/1.65 var(--font-body); }
a { color: var(--accent); }
:focus-visible { outline: 2px solid var(--accent); outline-offset: 2px; }

.bar {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px;
  padding: 12px 20px; background: var(--surface); border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; color: var(--fg); text-decoration: none; font: 800 1.15rem/1 var(--font-display); }
.mark { width: 28px; height: 28px; border-radius: 4px; background: linear-gradient(135deg, var(--accent) 0 55%, var(--accent-soft) 55%); }
.btn {
  display: inline-block; padding: 10px 16px; border-radius: 6px; text-decoration: none;
  background: var(--accent); color: var(--accent-ink); font: 600 .9rem/1 var(--font-body);
}

.article { max-width: 760px; margin: 0 auto; padding: 40px 20px 64px; }
.eyebrow { margin: 0 0 8px; color: var(--muted); font: 700 .75rem/1 var(--font-display); text-transform: uppercase; letter-spacing: .1em; }
h1 { margin: 0 0 14px; font: 800 clamp(1.9rem, 5vw, 2.7rem)/1.1 var(--font-display); letter-spacing: -0.02em; text-wrap: balance; }
h2 { margin: 44px 0 12px; font: 700 1.4rem/1.25 var(--font-display); text-wrap: balance; }
h3 { margin: 28px 0 8px; font: 700 1.05rem/1.3 var(--font-display); }
p, li { max-width: var(--measure); }
.lede { margin: 0 0 8px; font-size: 1.15rem; color: var(--muted); }
li + li { margin-top: 6px; }

.formula {
  margin: 16px 0; padding: 14px 16px; overflow-x: auto; white-space: pre;
  background: var(--surface); border: 1px solid var(--line); border-radius: 4px;
  font: .88rem/1.7 var(--font-data);
}
.table-wrap { overflow-x: auto; margin: 16px 0; }
table { width: 100%; border-collapse: collapse; font-size: .93rem; }
th {
  padding: 0 12px 8px 0; text-align: left; border-bottom: 2px solid var(--fg); color: var(--muted);
  font: 700 .72rem/1.2 var(--font-display); text-transform: uppercase; letter-spacing: .08em;
}
td { padding: 9px 12px 9px 0; border-bottom: 1px solid var(--line); vertical-align: top; }
.n { text-align: right; white-space: nowrap; font-family: var(--font-data); font-variant-numeric: tabular-nums; }
th.n { font-family: var(--font-display); }
tr.total td { font-weight: 700; border-bottom: 2px solid var(--fg); }

.note { padding: 14px 16px; background: var(--surface); border: 1px solid var(--line); border-radius: 4px; font-size: .92rem; }
.cta {
  display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 12px;
  margin-top: 48px; padding: 20px; border-radius: 6px; background: var(--accent-soft);
}
.cta p { margin: 0; font-weight: 600; }
.related { margin-top: 48px; padding-top: 20px; border-top: 1px solid var(--line); font-size: .95rem; }
.related h2 { margin-top: 0; font-size: 1rem; }
.updated { color: var(--muted); font-size: .85rem; }
.guide-list { padding: 0; list-style: none; display: grid; gap: 18px; margin-top: 28px; }
.site-footer { display: flex; flex-wrap: wrap; gap: 8px 20px; max-width: 760px; margin: 0 auto; padding: 24px 20px 40px; border-top: 1px solid var(--line); font-size: .85rem; color: var(--muted); }
.site-footer a { color: var(--fg); }