:root {
  --bg: #fbfbfa;
  --fg: #1d1d1f;
  --muted: #5f6368;
  --line: #d9d9d6;
  --panel: #ffffff;
  --accent: #1f5fa8;
  --accent-fg: #ffffff;
  --error: #b3261e;
  --ok: #1e7b3a;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #141517;
    --fg: #e8e8e6;
    --muted: #a0a4a8;
    --line: #34373b;
    --panel: #1c1e21;
    --accent: #7fb0ea;
    --accent-fg: #0d1b2a;
    --error: #f2877f;
    --ok: #7fd49a;
    color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #141517;
  --fg: #e8e8e6;
  --muted: #a0a4a8;
  --line: #34373b;
  --panel: #1c1e21;
  --accent: #7fb0ea;
  --accent-fg: #0d1b2a;
  --error: #f2877f;
  --ok: #7fd49a;
  color-scheme: dark;
}

* { box-sizing: border-box; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font: 16px/1.5 system-ui, -apple-system, "Segoe UI", sans-serif;
}
main { max-width: 860px; margin: 0 auto; padding: 24px 16px 48px; }
h1 { margin: 0 0 8px; font-size: 1.8rem; }
h2 { display: flex; align-items: center; gap: 10px; font-size: 1.3rem; margin: 0 0 12px; }
h3 { font-size: 1.05rem; margin: 20px 0 8px; }
a { color: var(--accent); }
.lede { color: var(--muted); margin: 0 0 12px; }
.step {
  display: inline-grid; place-items: center; width: 28px; height: 28px; border-radius: 50%;
  background: var(--accent); color: var(--accent-fg); font-size: 0.95rem;
}
section {
  background: var(--panel); border: 1px solid var(--line); border-radius: 10px;
  padding: 20px; margin: 20px 0;
}
.status { font-size: 0.92rem; color: var(--muted); }
.status.error, .error { color: var(--error); }
.hint { color: var(--muted); font-size: 0.92rem; }
.equation { font-family: ui-monospace, "SFMono-Regular", Menlo, monospace; overflow-wrap: anywhere; }
.row { display: flex; flex-wrap: wrap; gap: 16px; margin: 12px 0; }
.row label, label[data-option] { display: flex; flex-direction: column; gap: 4px; font-size: 0.9rem; }
[hidden] { display: none !important; }
input, select {
  font: inherit; color: inherit; background: var(--bg);
  border: 1px solid var(--line); border-radius: 6px; padding: 6px 8px; max-width: 100%;
}
input[type="number"] { width: 7em; }
button, .button {
  font: inherit; cursor: pointer; border-radius: 6px; padding: 8px 14px;
  border: 1px solid var(--line); background: var(--bg); color: inherit; text-decoration: none; display: inline-block;
}
.primary { background: var(--accent); color: var(--accent-fg); border-color: var(--accent); }
button:disabled { opacity: 0.5; cursor: progress; }
.link { border: none; background: none; color: var(--accent); padding: 4px; }
.factors { border-collapse: collapse; margin-bottom: 4px; }
.factors th { text-align: left; font-weight: 600; font-size: 0.85rem; color: var(--muted); padding: 0 6px 4px 0; }
.factors td { padding: 2px 6px 2px 0; }
.scroll { overflow-x: auto; margin: 12px 0; }
table.data { border-collapse: collapse; font-size: 0.9rem; font-variant-numeric: tabular-nums; }
table.data th, table.data td { border-bottom: 1px solid var(--line); padding: 4px 10px; text-align: right; }
table.data th:first-child, table.data td:first-child { text-align: left; }
.drop {
  display: block; border: 2px dashed var(--line); border-radius: 10px; padding: 28px 16px;
  text-align: center; color: var(--muted); cursor: pointer;
}
.drop.over { border-color: var(--accent); color: var(--fg); }
.drop input { display: block; margin: 0 auto 8px; }
.sr { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); }
footer { color: var(--muted); font-size: 0.88rem; }