:root {
  color-scheme: dark;
  --bg: #050914;
  --surface: #0b1220;
  --surface-2: #101b2e;
  --ink: #f7f9fc;
  --text: #c5d0df;
  --muted: #8795aa;
  --line: rgba(255, 255, 255, 0.13);
  --blue: #5aaaf0;
  --blue-strong: #2f8bd3;
  --gold: #e7bd48;
  --green: #61d6a4;
  --max: 1080px;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  min-height: 100vh;
  color: var(--text);
  background:
    radial-gradient(circle at 88% 4%, rgba(47, 139, 211, 0.17), transparent 34rem),
    radial-gradient(circle at 8% 36%, rgba(90, 170, 240, 0.08), transparent 28rem),
    var(--bg);
  line-height: 1.65;
}
a { color: var(--blue); }
a:hover { color: #91ccff; }
img { max-width: 100%; }
.skip-link { position: absolute; left: -9999px; top: 0; }
.skip-link:focus { left: 1rem; top: 1rem; z-index: 10; padding: .7rem 1rem; color: var(--ink); background: var(--surface); }
.site-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1.5rem;
  max-width: var(--max);
  margin: 0 auto;
  padding: 1.25rem 1.5rem;
  border-bottom: 1px solid var(--line);
}
.brand { display: inline-flex; align-items: center; gap: .7rem; color: var(--ink); font-size: 1.15rem; font-weight: 750; text-decoration: none; }
.brand img { width: 38px; height: 38px; }
.site-nav { display: flex; flex-wrap: wrap; align-items: center; justify-content: flex-end; gap: 1rem; }
.site-nav a { color: var(--text); font-size: .92rem; text-decoration: none; }
.site-nav .nav-cta { padding: .55rem .85rem; color: #04101b; background: var(--blue); border-radius: 999px; font-weight: 750; }
.page { max-width: var(--max); margin: 0 auto; padding: 4.75rem 1.5rem 5rem; }
.hero { max-width: 820px; }
.eyebrow { margin: 0 0 1rem; color: var(--blue); font-size: .77rem; font-weight: 800; letter-spacing: .15em; text-transform: uppercase; }
h1, h2, h3 { color: var(--ink); line-height: 1.13; letter-spacing: -.025em; }
h1 { max-width: 820px; margin: 0; font-size: clamp(2.6rem, 8vw, 5.4rem); }
h2 { margin: 0 0 1rem; font-size: clamp(1.8rem, 4vw, 3rem); }
h3 { margin: 0 0 .55rem; font-size: 1.2rem; }
.lede { max-width: 740px; margin: 1.4rem 0 0; color: var(--text); font-size: clamp(1.05rem, 2vw, 1.3rem); }
.meta { display: flex; flex-wrap: wrap; gap: .65rem 1.1rem; margin: 1.4rem 0 0; color: var(--muted); font-size: .88rem; }
.hero-actions { display: flex; flex-wrap: wrap; gap: .8rem; margin-top: 1.8rem; }
.button { display: inline-flex; align-items: center; justify-content: center; min-height: 46px; padding: .75rem 1rem; border: 1px solid var(--line); border-radius: 12px; color: var(--ink); background: var(--surface); font-weight: 750; text-decoration: none; }
.button.primary { color: #04101b; border-color: transparent; background: var(--blue); }
.content-grid { display: grid; grid-template-columns: minmax(0, 1fr) 270px; gap: 4rem; margin-top: 4rem; align-items: start; }
.article { min-width: 0; }
.article section { padding: 2.2rem 0; border-top: 1px solid var(--line); }
.article section:first-child { padding-top: 0; border-top: 0; }
.article p, .article li { font-size: 1rem; }
.article li + li { margin-top: .55rem; }
.article table { width: 100%; border-collapse: collapse; margin: 1.25rem 0; }
.article th, .article td { padding: .8rem; text-align: left; border: 1px solid var(--line); }
.article th { color: var(--ink); background: var(--surface-2); }
.article blockquote, .note { margin: 1.35rem 0; padding: 1rem 1.1rem; border-left: 3px solid var(--blue); border-radius: 0 12px 12px 0; background: rgba(90, 170, 240, .08); }
.note.warning { border-color: var(--gold); background: rgba(231, 189, 72, .08); }
.toc { position: sticky; top: 1rem; padding: 1.15rem; border: 1px solid var(--line); border-radius: 16px; background: rgba(11, 18, 32, .82); backdrop-filter: blur(10px); }
.toc strong { display: block; margin-bottom: .7rem; color: var(--ink); }
.toc a { display: block; margin: .45rem 0; color: var(--text); font-size: .9rem; text-decoration: none; }
.card-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin: 1.4rem 0; }
.card { padding: 1.15rem; border: 1px solid var(--line); border-radius: 16px; background: linear-gradient(145deg, rgba(16, 27, 46, .86), rgba(8, 14, 25, .76)); }
.card p { margin-bottom: 0; color: var(--muted); font-size: .93rem; }
.formula { padding: 1.15rem; overflow-x: auto; border: 1px solid rgba(90, 170, 240, .35); border-radius: 16px; color: var(--ink); background: rgba(90, 170, 240, .08); font-family: ui-monospace, SFMono-Regular, Menlo, monospace; font-size: clamp(.96rem, 2.3vw, 1.2rem); }
.calculator { display: grid; gap: 1.15rem; max-width: 680px; padding: 1.4rem; border: 1px solid var(--line); border-radius: 20px; background: var(--surface); box-shadow: 0 24px 70px rgba(0, 0, 0, .25); }
.calculator label { display: grid; gap: .45rem; color: var(--ink); font-weight: 700; }
.calculator label span { color: var(--muted); font-size: .86rem; font-weight: 500; }
.calculator input { width: 100%; min-height: 48px; padding: .72rem .85rem; border: 1px solid var(--line); border-radius: 11px; color: var(--ink); background: #060c17; font: inherit; }
.calculator input:focus { outline: 2px solid var(--blue); outline-offset: 2px; }
.calculator button { min-height: 48px; border: 0; border-radius: 11px; color: #04101b; background: var(--blue); font: inherit; font-weight: 800; cursor: pointer; }
.calculator-result { min-height: 118px; padding: 1rem; border: 1px solid var(--line); border-radius: 14px; background: #060c17; }
.calculator-result output { display: block; color: var(--ink); font-size: 2.5rem; font-weight: 850; line-height: 1; }
.calculator-result .result-band { display: inline-block; margin-top: .65rem; padding: .25rem .55rem; border-radius: 999px; color: #04101b; background: var(--green); font-size: .8rem; font-weight: 850; }
.calculator-result p { margin-bottom: 0; color: var(--muted); }
.sources { padding-left: 1.2rem; }
.sources a { overflow-wrap: anywhere; }
.disclosure { margin-top: 3rem; padding: 1.2rem; border: 1px solid var(--line); border-radius: 16px; color: var(--muted); background: rgba(11, 18, 32, .72); font-size: .9rem; }
.related { margin-top: 4rem; padding-top: 2.5rem; border-top: 1px solid var(--line); }
.site-footer { display: flex; flex-wrap: wrap; justify-content: space-between; gap: 1rem 2rem; max-width: var(--max); margin: 0 auto; padding: 2rem 1.5rem 3rem; border-top: 1px solid var(--line); color: var(--muted); font-size: .88rem; }
.site-footer nav { display: flex; flex-wrap: wrap; gap: .85rem; }
.site-footer a { color: var(--text); }

@media (max-width: 800px) {
  .content-grid { grid-template-columns: 1fr; gap: 2rem; }
  .toc { position: static; order: -1; }
  .card-grid { grid-template-columns: 1fr; }
}

@media (max-width: 620px) {
  .site-header { align-items: flex-start; }
  .site-nav { gap: .65rem; }
  .site-nav a:not(.nav-cta) { display: none; }
  .page { padding-top: 3.3rem; }
  h1 { font-size: clamp(2.45rem, 13vw, 4rem); }
  .article table { display: block; overflow-x: auto; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}