style.css

:root {
  color-scheme: light;
  --paper: #f2efe6;
  --surface: #fffdf7;
  --surface-muted: #e7e4da;
  --ink: #17251f;
  --muted: #5b6760;
  --line: #cbc7bb;
  --spruce: #1d6753;
  --spruce-deep: #144b3d;
  --spruce-soft: #d8e7df;
  --clay: #b65d35;
  --clay-soft: #f1ded3;
  --gold: #9b7a30;
  --shadow: 0 20px 56px rgb(28 43 35 / 11%);
  --radius-small: 6px;
  --radius-large: 16px;
  --display: Georgia, "Times New Roman", serif;
  --body: Aptos, "Segoe UI", sans-serif;
  --mono: "Cascadia Mono", Consolas, monospace;
}

[data-theme="dark"] {
  color-scheme: dark;
  --paper: #14201b;
  --surface: #1c2a24;
  --surface-muted: #26362f;
  --ink: #edf1eb;
  --muted: #b5c0b9;
  --line: #405048;
  --spruce: #78c2a5;
  --spruce-deep: #a4d8c3;
  --spruce-soft: #29493d;
  --clay: #ed9568;
  --clay-soft: #523629;
  --gold: #d0b66d;
  --shadow: 0 20px 56px rgb(0 0 0 / 28%);
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background:
    linear-gradient(rgb(23 37 31 / 3.5%) 1px, transparent 1px),
    linear-gradient(90deg, rgb(23 37 31 / 3.5%) 1px, transparent 1px),
    var(--paper);
  background-size: 32px 32px;
  color: var(--ink);
  font-family: var(--body);
  font-size: 17px;
  line-height: 1.55;
  text-wrap: pretty;
}

button, input, select { font: inherit; }
button, input, select, summary, a { -webkit-tap-highlight-color: transparent; }
:focus-visible { outline: 3px solid var(--clay); outline-offset: 3px; }
[hidden] { display: none !important; }
.shell { width: min(1220px, calc(100% - 32px)); margin-inline: auto; }

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 66px;
  border-bottom: 1px solid var(--line);
}
.wordmark {
  color: var(--ink);
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 750;
  letter-spacing: .09em;
  text-decoration: none;
}
.top-actions { display: flex; align-items: center; gap: 12px; }
.status { color: var(--muted); font-family: var(--mono); font-size: 11px; letter-spacing: .04em; }
.status.ready { color: var(--spruce); }
.status.error { color: var(--clay); }

.quiet-button {
  min-height: 44px;
  padding: 8px 13px;
  border: 1px solid var(--line);
  border-radius: var(--radius-small);
  background: var(--surface);
  color: var(--ink);
  cursor: pointer;
  transition: transform 160ms ease, border-color 160ms ease, background 160ms ease;
}
.quiet-button:hover { border-color: var(--spruce); background: var(--spruce-soft); }
.quiet-button:active { transform: translateY(1px); }
.quiet-button:disabled { cursor: not-allowed; opacity: .5; }

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.5fr) minmax(300px, .7fr);
  gap: clamp(36px, 7vw, 92px);
  align-items: end;
  padding-block: clamp(62px, 9vw, 118px) 48px;
}
.eyebrow {
  margin: 0 0 13px;
  color: var(--spruce);
  font-family: var(--mono);
  font-size: 11px;
  font-weight: 750;
  letter-spacing: .12em;
  text-transform: uppercase;
}
h1, h2, h3 { font-family: var(--display); font-weight: 500; line-height: 1.08; }
h1 { margin: 0; font-size: clamp(44px, 7vw, 84px); letter-spacing: -.047em; }
h1 em { color: var(--spruce-deep); font-weight: inherit; }
h2 { margin: 0; font-size: clamp(29px, 4vw, 45px); letter-spacing: -.028em; }
h3 { margin: 0; font-size: 27px; }
.lede { max-width: 820px; margin: 25px 0 0; color: var(--muted); font-size: clamp(18px, 2.1vw, 23px); }
.endpoint-note { padding: 25px; border-top: 4px solid var(--clay); background: var(--surface); box-shadow: var(--shadow); }
.endpoint-note span { display: block; margin-bottom: 9px; color: var(--clay); font-family: var(--mono); font-size: 11px; font-weight: 750; letter-spacing: .1em; text-transform: uppercase; }
.endpoint-note p { margin: 0; }

.evidence-strip { display: grid; grid-template-columns: repeat(4, 1fr); margin-bottom: 38px; border: 1px solid var(--line); background: var(--surface); }
.evidence-item { min-height: 132px; padding: 23px; border-right: 1px solid var(--line); }
.evidence-item:last-child { border-right: 0; }
.evidence-item strong { display: block; margin-bottom: 8px; font-family: var(--display); font-size: 36px; font-weight: 500; line-height: 1; }
.evidence-item span { color: var(--muted); font-size: 14px; }

.warning { display: grid; grid-template-columns: auto 1fr; gap: 17px; margin-bottom: 40px; padding: 23px 25px; border: 1px solid color-mix(in srgb, var(--clay) 45%, var(--line)); border-radius: var(--radius-small); background: var(--clay-soft); }
.warning span { color: var(--clay); font-family: var(--mono); font-size: 12px; font-weight: 750; letter-spacing: .09em; }
.warning p { margin: 0; }

.workspace { overflow: hidden; margin-bottom: 68px; border: 1px solid var(--line); border-radius: var(--radius-large); background: var(--surface); box-shadow: var(--shadow); }
.tabs { display: flex; border-bottom: 1px solid var(--line); background: var(--surface-muted); }
.tab { min-height: 56px; padding: 12px 24px; border: 0; border-right: 1px solid var(--line); background: transparent; color: var(--muted); cursor: pointer; font-weight: 700; }
.tab:hover { background: var(--surface); color: var(--ink); }
.tab[aria-selected="true"] { background: var(--surface); color: var(--spruce-deep); box-shadow: inset 0 -3px var(--spruce); }
.panel { display: none; }
.panel.active { display: block; animation: enter 220ms ease both; }
@keyframes enter { from { opacity: 0; transform: translateY(4px); } to { opacity: 1; transform: none; } }

.tool-grid { display: grid; grid-template-columns: minmax(0, 1.08fr) minmax(380px, .92fr); min-height: 720px; }
.form-pane, .curve-controls { padding: clamp(25px, 4vw, 46px); border-right: 1px solid var(--line); }
.result-pane, .chart-pane { padding: clamp(25px, 4vw, 46px); background: color-mix(in srgb, var(--spruce-soft) 28%, var(--surface)); }
.section-heading { margin-bottom: 31px; }
.section-heading > p:last-child { margin: 10px 0 0; color: var(--muted); }
.field-groups { display: grid; gap: 24px; }
fieldset { margin: 0; padding: 0; border: 0; }
legend { width: 100%; margin-bottom: 13px; padding-bottom: 8px; border-bottom: 1px solid var(--line); color: var(--spruce-deep); font-family: var(--mono); font-size: 11px; font-weight: 750; letter-spacing: .09em; text-transform: uppercase; }
.fields { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 15px 17px; }
.fields.three { grid-template-columns: repeat(3, minmax(0, 1fr)); }
.field { min-width: 0; }
label { display: block; margin-bottom: 6px; font-size: 14px; font-weight: 700; }
input, select { width: 100%; min-height: 46px; padding: 9px 11px; border: 1px solid var(--line); border-radius: var(--radius-small); background: var(--surface); color: var(--ink); transition: border-color 160ms ease, box-shadow 160ms ease; }
input:hover, select:hover { border-color: var(--spruce); }
input:focus, select:focus { border-color: var(--spruce); box-shadow: 0 0 0 3px color-mix(in srgb, var(--spruce) 18%, transparent); outline: 0; }
.range { display: block; margin-top: 5px; color: var(--muted); font-family: var(--mono); font-size: 10px; }
.primary-button { width: 100%; min-height: 54px; margin-top: 28px; border: 1px solid var(--spruce-deep); border-radius: var(--radius-small); background: var(--spruce-deep); color: var(--surface); cursor: pointer; font-weight: 750; transition: transform 160ms ease, filter 160ms ease, box-shadow 160ms ease; }
[data-theme="dark"] .primary-button { color: #14211b; }
.primary-button:hover { filter: brightness(1.08); box-shadow: 0 11px 26px rgb(20 75 61 / 18%); transform: translateY(-1px); }
.primary-button:active { transform: translateY(1px); }
.primary-button:disabled { cursor: wait; opacity: .58; transform: none; }

.empty-state { min-height: 430px; display: grid; place-content: center; justify-items: center; text-align: center; color: var(--muted); }
.loading-ring { width: 74px; height: 74px; margin-bottom: 22px; border: 1px solid var(--line); border-top-color: var(--spruce); border-radius: 50%; animation: spin 1.2s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }
.result-kicker { margin: 0; color: var(--spruce-deep); font-family: var(--mono); font-size: 11px; font-weight: 750; letter-spacing: .1em; text-transform: uppercase; }
.prediction { margin: 11px 0 24px; font-family: var(--display); font-size: clamp(58px, 7vw, 82px); line-height: .95; letter-spacing: -.045em; }
.prediction small { display: block; margin-top: 9px; color: var(--muted); font-family: var(--body); font-size: 16px; letter-spacing: 0; }
.comparison { display: flex; justify-content: space-between; gap: 20px; margin-bottom: 24px; padding-block: 14px; border-block: 1px solid var(--line); }
.comparison span { color: var(--muted); }
.interval-grid { display: grid; gap: 12px; }
.interval-grid article { padding: 18px; border: 1px solid var(--line); border-radius: var(--radius-small); background: var(--surface); }
.interval-grid article > span, .interval-grid small { display: block; color: var(--muted); font-size: 13px; }
.interval-grid strong { display: block; margin: 5px 0; font-family: var(--display); font-size: 24px; font-weight: 500; }
.interval-grid .stress-card { border-color: color-mix(in srgb, var(--clay) 42%, var(--line)); background: var(--clay-soft); }
.notes { margin-top: 20px; padding: 18px; border: 1px solid var(--line); border-radius: var(--radius-small); background: var(--surface); }
.notes h4 { margin: 0 0 9px; font-size: 15px; }
.notes ul { margin: 0; padding-left: 20px; }
.notes li + li { margin-top: 6px; }
.decision-boundary { margin: 20px 0 0; color: var(--muted); font-size: 13px; }
.error-block { padding: 18px; border: 1px solid var(--clay); border-radius: var(--radius-small); background: var(--clay-soft); }

.curve-layout { display: grid; grid-template-columns: minmax(390px, .72fr) minmax(0, 1.28fr); min-height: 760px; }
.time-controls { margin-top: 26px; }
.checkbox-row { display: flex; align-items: flex-start; gap: 10px; margin-top: 15px; font-weight: 500; }
.checkbox-row input { flex: 0 0 auto; width: 18px; min-height: 18px; margin-top: 3px; }
.chart-header { display: flex; align-items: flex-end; justify-content: space-between; gap: 20px; margin-bottom: 20px; }
.chart-card { min-height: 430px; padding: 14px; border: 1px solid var(--line); border-radius: var(--radius-small); background: var(--surface); }
#curveChart { display: block; width: 100%; height: auto; overflow: visible; }
.legend { display: flex; flex-wrap: wrap; gap: 12px 19px; margin-top: 14px; color: var(--muted); font-size: 12px; }
.legend span::before { content: ""; display: inline-block; width: 24px; height: 3px; margin-right: 7px; vertical-align: middle; background: var(--spruce); }
.legend .legend-baseline::before { background: repeating-linear-gradient(90deg, var(--gold) 0 6px, transparent 6px 9px); }
.legend .legend-represented::before { height: 10px; border: 1px solid var(--spruce); background: var(--spruce-soft); }
.legend .legend-stress::before { height: 10px; border: 1px solid var(--clay); background: var(--clay-soft); }

.methods { display: grid; grid-template-columns: .67fr 1.33fr; gap: clamp(34px, 7vw, 86px); padding-block: 24px 92px; }
.method-details details { border-top: 1px solid var(--line); }
.method-details details:last-child { border-bottom: 1px solid var(--line); }
summary { padding: 19px 0; cursor: pointer; font-weight: 750; list-style: none; }
summary::after { content: "+"; float: right; color: var(--spruce); font-family: var(--mono); }
details[open] summary::after { content: "−"; }
details p { margin: 0 0 21px; color: var(--muted); }
footer { padding-block: 30px 45px; border-top: 1px solid var(--line); color: var(--muted); font-size: 14px; }
footer a { color: var(--spruce-deep); }

@media (max-width: 960px) {
  .hero, .tool-grid, .curve-layout, .methods { grid-template-columns: 1fr; }
  .evidence-strip { grid-template-columns: repeat(2, 1fr); }
  .evidence-item:nth-child(2) { border-right: 0; }
  .evidence-item:nth-child(-n+2) { border-bottom: 1px solid var(--line); }
  .form-pane, .curve-controls { border-right: 0; border-bottom: 1px solid var(--line); }
  .result-pane { min-height: 560px; }
}

@media (max-width: 620px) {
  body { font-size: 16px; }
  .shell { width: min(100% - 20px, 1220px); }
  .topbar { min-height: 60px; }
  .status { display: none; }
  .hero { padding-top: 48px; }
  .evidence-strip, .fields, .fields.three { grid-template-columns: 1fr; }
  .evidence-item { border-right: 0; border-bottom: 1px solid var(--line); }
  .evidence-item:last-child { border-bottom: 0; }
  .warning { grid-template-columns: 1fr; }
  .tabs { overflow-x: auto; }
  .tab { flex: 1 0 auto; min-height: 50px; padding: 10px 15px; }
  .form-pane, .result-pane, .curve-controls, .chart-pane { padding: 24px 18px; }
  .chart-header { align-items: flex-start; flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation: none !important; transition-duration: .01ms !important; }
}