:root {
  --bg: #EEF2F0;
  --surface: #FFFFFF;
  --fg: #15231F;
  --muted: #55655F;
  --line: #CBD7D2;
  --accent: #0E6B5A;
  --accent-fg: #FFFFFF;
  --accent-soft: #D7EDE7;
  --warn: #B4412B;
  --font-display: "Bricolage Grotesque", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "IBM Plex Mono", ui-monospace, "SFMono-Regular", Menlo, Consolas, monospace;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root {
    --bg: #0F1715;
    --surface: #16211E;
    --fg: #E7F0EC;
    --muted: #93A59F;
    --line: #2A3A35;
    --accent: #5FD0B5;
    --accent-fg: #0B1512;
    --accent-soft: #1F3730;
    --warn: #F08A72;
    color-scheme: dark;
  }
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-display);
  font-size: 1rem;
  line-height: 1.55;
  padding-inline: 16px;
  padding-block: 20px 48px;
}
a { color: var(--accent); }
.wrap { max-width: 720px; margin: 0 auto; display: flex; flex-direction: column; gap: 22px; }

.site-top { display: flex; flex-direction: column; gap: 10px; padding-bottom: 14px; border-bottom: 1px solid var(--line); }
.brand { font-weight: 700; font-size: 1.05rem; letter-spacing: -0.01em; color: var(--fg); text-decoration: none; }
.nav { display: flex; flex-wrap: wrap; gap: 6px 16px; font-size: 0.9rem; }
.nav a { color: var(--muted); text-decoration: none; font-weight: 600; }
.nav a:hover { color: var(--accent); }
.nav a[aria-current="page"] { color: var(--fg); text-decoration: underline; text-underline-offset: 4px; text-decoration-color: var(--accent); text-decoration-thickness: 2px; }

header.intro { display: flex; flex-direction: column; gap: 6px; }
h1 { margin: 0; font-size: clamp(1.9rem, 6vw, 2.75rem); line-height: 1.05; font-weight: 700; letter-spacing: -0.02em; text-wrap: balance; }
.lede { margin: 0; color: var(--muted); max-width: 55ch; }

.tabs { display: grid; grid-template-columns: repeat(4, 1fr); gap: 6px; }
.tab {
  font: 600 0.9rem/1.25 var(--font-display);
  text-align: left;
  padding: 10px 12px;
  min-height: 3rem;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--fg);
  cursor: pointer;
}
.tab:hover { border-color: var(--accent); }
.tab[aria-selected="true"] { background: var(--accent); border-color: var(--accent); color: var(--accent-fg); }
.tab:focus-visible, .chip:focus-visible, .seg button:focus-visible, .copy:focus-visible, .nav a:focus-visible, .card:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.panel { background: var(--surface); border: 1px solid var(--line); border-radius: 12px; padding: 20px; display: flex; flex-direction: column; gap: 18px; }
.question { display: flex; flex-wrap: wrap; align-items: flex-end; gap: 12px 10px; }
.word { height: 3.25rem; line-height: 3.25rem; font-size: 1.125rem; font-weight: 600; }
.field { display: flex; flex-direction: column; gap: 4px; min-width: 0; }
.field label { font-size: 0.72rem; font-weight: 600; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); }
.box { display: flex; align-items: center; gap: 4px; height: 3.25rem; padding-inline: 12px; border: 1.5px solid var(--line); border-radius: 8px; background: var(--bg); }
.box:focus-within { border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
.box input { width: 6.5em; min-width: 0; border: 0; outline: none; background: transparent; color: var(--fg); font: 600 1.375rem/1 var(--font-mono); font-variant-numeric: tabular-nums; }
.suf { font: 600 1.25rem/1 var(--font-mono); color: var(--muted); }

.seg { display: flex; height: 3.25rem; border: 1.5px solid var(--line); border-radius: 8px; overflow: hidden; }
.seg button { font: 600 1rem var(--font-display); padding-inline: 14px; border: 0; background: var(--bg); color: var(--fg); cursor: pointer; }
.seg button[aria-pressed="true"] { background: var(--accent); color: var(--accent-fg); }

.quick { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; }
.quick[hidden] { display: none; }
.quick .qlabel { font-size: 0.85rem; color: var(--muted); margin-right: 2px; }
.chip { font: 600 0.9rem var(--font-mono); padding: 6px 10px; border: 1px solid var(--line); border-radius: 6px; background: var(--bg); color: var(--fg); cursor: pointer; }
.chip:hover { border-color: var(--accent); }
.chip[aria-pressed="true"] { background: var(--accent-soft); border-color: var(--accent); }

.answer { border-top: 1px solid var(--line); padding-top: 18px; display: flex; flex-direction: column; gap: 12px; }
.answer-row { display: flex; flex-wrap: wrap; align-items: baseline; justify-content: space-between; gap: 8px 16px; }
.result { font: 600 clamp(2.25rem, 10vw, 3.5rem)/1.05 var(--font-mono); letter-spacing: -0.03em; font-variant-numeric: tabular-nums; color: var(--accent); overflow-wrap: anywhere; min-width: 0; }
.result.empty { color: var(--muted); }
.result .unit { font-size: 0.6em; margin-left: 2px; }
.copy { font: 600 0.85rem var(--font-display); padding: 7px 12px; border: 1px solid var(--line); border-radius: 6px; background: var(--bg); color: var(--fg); cursor: pointer; }
.copy:hover { border-color: var(--accent); }
.copy[hidden] { display: none; }
.caption { margin: 0; font-size: 1.0625rem; }
.caption.error { color: var(--warn); }
.formula { margin: 0; padding: 8px 10px; border-radius: 6px; background: var(--bg); font: 500 0.875rem/1.5 var(--font-mono); color: var(--muted); overflow-wrap: anywhere; }
.formula[hidden] { display: none; }
.bars { display: flex; flex-direction: column; gap: 8px; }
.bar { display: grid; grid-template-columns: 5.5rem minmax(0, 1fr) auto; align-items: center; gap: 10px; font-size: 0.875rem; }
.bar .name { color: var(--muted); font-weight: 600; }
.bar .track { height: 14px; border-radius: 4px; background: var(--accent-soft); overflow: hidden; }
.bar .fill { height: 100%; width: 0; border-radius: 4px; background: var(--accent); transition: width 0.3s ease; }
.bar .fill.down { background: var(--warn); }
.bar .val { font-family: var(--font-mono); font-weight: 500; font-variant-numeric: tabular-nums; text-align: right; }
.note { margin: 0; font-size: 0.8rem; color: var(--muted); }
.note[hidden] { display: none; }

.content { display: flex; flex-direction: column; gap: 14px; max-width: 65ch; padding-top: 6px; }
.content h2 { margin: 14px 0 0; font-size: 1.5rem; line-height: 1.2; letter-spacing: -0.01em; text-wrap: balance; }
.content h3 { margin: 8px 0 0; font-size: 1.1rem; line-height: 1.3; }
.content p, .content ul, .content ol { margin: 0; }
.content ul, .content ol { padding-left: 1.25rem; display: flex; flex-direction: column; gap: 6px; }
.formula-box { padding: 10px 14px; border-left: 3px solid var(--accent); background: var(--surface); font: 500 0.95rem/1.5 var(--font-mono); overflow-wrap: anywhere; }
.content .qa { display: flex; flex-direction: column; gap: 4px; }

.related h2 { margin: 0 0 10px; font-size: 1.25rem; }
.cards { display: grid; grid-template-columns: repeat(auto-fit, minmax(200px, 1fr)); gap: 10px; }
.card { display: flex; flex-direction: column; gap: 2px; padding: 12px 14px; border: 1px solid var(--line); border-radius: 8px; background: var(--surface); color: var(--fg); text-decoration: none; }
.card:hover { border-color: var(--accent); }
.card strong { font-size: 0.98rem; }
.card span { font-size: 0.85rem; color: var(--muted); }

.site-foot { display: flex; flex-wrap: wrap; gap: 8px 18px; padding-top: 16px; border-top: 1px solid var(--line); font-size: 0.85rem; color: var(--muted); }
.site-foot a { color: var(--muted); }
.site-foot a:hover { color: var(--accent); }

@media (max-width: 560px) {
  .tabs { grid-template-columns: repeat(2, 1fr); }
  .panel { padding: 16px; }
  .bar { grid-template-columns: 4.5rem minmax(0, 1fr) auto; }
}
@media (prefers-reduced-motion: reduce) {
  .bar .fill { transition: none; }
}