:root {
  color-scheme: light;
  --paper: #f5f4ef;
  --surface: #fbfaf6;
  --ink: #222824;
  --muted: #687069;
  --line: #cfd3cc;
  --line-strong: #9fa79f;
  --accent: #245b49;
  --accent-soft: #e2ebe5;
  --accent-two: #a36b35;
  --accent-two-soft: #f2e9dd;
  --danger: #9b2f2f;
  --danger-soft: #f8e9e7;
  --symbol-font: ui-monospace, "SFMono-Regular", Consolas, "Liberation Mono", monospace;
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", "Noto Sans JP", "Hiragino Kaku Gothic ProN", Meiryo, sans-serif;
}

* { box-sizing: border-box; }
button, input, textarea { font: inherit; }
a { color: inherit; }
:focus-visible { outline: 3px solid var(--accent); outline-offset: 3px; }

.intro { margin-bottom: 18px; }
.lead { max-width: 780px; }

.tool-shell {
  display: grid;
  grid-template-columns: minmax(0, .98fr) minmax(0, 1.02fr);
  border: 1px solid var(--line-strong);
  background: var(--surface);
}
.calculator-panel,
.visual-panel { min-width: 0; padding: 24px; }
.calculator-panel { border-right: 1px solid var(--line); }

.section-heading { margin-bottom: 16px; }
.section-heading h2,
.visual-heading-row h2,
.content-section h2 { margin: 0; font-size: clamp(1.2rem, 2vw, 1.48rem); line-height: 1.35; }
.field-group { min-width: 0; margin-top: 17px; }
.field-group:first-of-type { margin-top: 0; }
.field-group label { display: block; margin-bottom: 6px; font-weight: 760; }
.optional { color: var(--muted); font-size: .82em; font-weight: 500; }
textarea,
.unit-input {
  display: block;
  width: 100%;
  min-width: 0;
  border: 1px solid var(--line-strong);
  border-radius: 0;
  padding: 10px 11px;
  color: var(--ink);
  background: #fff;
}
textarea {
  min-height: 146px;
  resize: vertical;
  font-family: var(--symbol-font);
  line-height: 1.55;
  tab-size: 4;
}
.unit-input { min-height: 44px; }
textarea:focus,
.unit-input:focus { border-color: var(--accent); box-shadow: 0 0 0 3px rgba(36, 91, 73, .16); outline: 0; }
textarea[aria-invalid="true"],
.unit-input[aria-invalid="true"] { border-color: var(--danger); background: #fff8f8; }
.field-help,
.field-error,
.form-note { overflow-wrap: anywhere; }
.field-help { margin: 6px 0 0; color: var(--muted); font-size: .78rem; line-height: 1.6; }
.field-error { min-height: 1.2em; margin: 3px 0 0; color: var(--danger); font-size: .8rem; line-height: 1.45; }
.form-note {
  margin: 17px 0 0;
  padding: 9px 11px;
  border-left: 3px solid var(--line-strong);
  color: var(--muted);
  font-size: .8rem;
}
.form-error {
  margin: 13px 0 0;
  padding: 10px 12px;
  border-left: 4px solid var(--danger);
  background: var(--danger-soft);
  color: #762525;
  font-weight: 700;
  line-height: 1.55;
}
.form-error[hidden] { display: none; }
.form-actions { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 18px; }
.button {
  min-height: 44px;
  padding: 9px 16px;
  border: 1px solid var(--accent);
  border-radius: 0;
  cursor: pointer;
  font-weight: 760;
}
.button-primary { color: #fff; background: var(--accent); }
.button-primary:hover { background: #173f32; }
.button-secondary { color: var(--accent); background: transparent; }
.button:hover:not(:disabled) { border-color: var(--ink); }

.result-box {
  margin-top: 20px;
  padding: 16px;
  border: 1px solid var(--line-strong);
  border-left: 4px solid var(--accent);
  background: #fff;
}
.result-box[data-state="ready"] { border-color: var(--accent); background: var(--accent-soft); }
.result-box[data-state="error"] { border-color: var(--danger); background: var(--danger-soft); }
.result-label { margin: 0; color: var(--muted); font-size: .78rem; font-weight: 760; }
.result-value { display: block; margin-top: 3px; overflow-wrap: anywhere; font-size: clamp(1.2rem, 2.6vw, 1.75rem); font-weight: 800; line-height: 1.35; }
.result-status { margin: 4px 0 0; color: var(--muted); font-size: .82rem; line-height: 1.6; }
.series-results { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; margin-top: 16px; }
.series-card {
  min-width: 0;
  padding: 13px;
  border: 1px solid var(--accent);
  background: var(--surface);
}
.series-card-b { border-color: var(--accent-two); background: #fffdf9; }
.series-card-heading { display: flex; align-items: baseline; justify-content: space-between; gap: 8px; }
.series-card-heading h3 { margin: 0; font-size: 1rem; }
.series-unit { max-width: 55%; color: var(--muted); font-size: .78rem; overflow-wrap: anywhere; text-align: right; }
.result-details {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin: 11px 0 0;
  border-top: 1px solid var(--line);
  border-left: 1px solid var(--line);
}
.result-details div {
  min-width: 0;
  padding: 8px 9px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.result-details .detail-wide { grid-column: 1 / -1; }
.result-details dt { color: var(--muted); font-size: .7rem; line-height: 1.35; }
.result-details dd { margin: 3px 0 0; overflow-wrap: anywhere; font-size: .9rem; font-weight: 760; line-height: 1.45; }
.comparison-box {
  margin-top: 14px;
  padding: 13px;
  border: 1px solid var(--accent-two);
  background: var(--accent-two-soft);
}
.comparison-box h3 { margin: 0; font-size: 1rem; }
.comparison-formula { margin: 3px 0 0; color: var(--muted); font-family: var(--symbol-font); font-size: .82rem; }
.comparison-details {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin: 11px 0 0;
  border-top: 1px solid rgba(163, 107, 53, .35);
  border-left: 1px solid rgba(163, 107, 53, .35);
}
.comparison-details div { min-width: 0; padding: 8px 9px; border-right: 1px solid rgba(163, 107, 53, .35); border-bottom: 1px solid rgba(163, 107, 53, .35); }
.comparison-details dt { color: var(--muted); font-size: .7rem; line-height: 1.35; }
.comparison-details dd { margin: 3px 0 0; overflow-wrap: anywhere; font-size: .9rem; font-weight: 760; }
.result-notes { margin: 13px 0 0; padding-left: 1.2em; color: var(--muted); font-size: .76rem; line-height: 1.55; }
.result-notes:empty { display: none; }

.visual-heading-row { display: flex; align-items: flex-start; justify-content: space-between; gap: 12px; }
.status-badge { padding: 5px 9px; border: 1px solid var(--line-strong); color: var(--muted); font-size: .72rem; font-weight: 760; white-space: nowrap; }
.status-badge[data-state="ready"] { border-color: var(--accent); background: var(--accent-soft); color: var(--accent); }
.status-badge[data-state="error"] { border-color: var(--danger); background: var(--danger-soft); color: var(--danger); }
.visual-legend {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 13px;
  color: var(--muted);
  font-size: .78rem;
}
.visual-legend > span { display: inline-flex; align-items: center; gap: 5px; }
.legend-dot { width: 10px; height: 10px; border-radius: 50%; background: var(--accent); }
.legend-dot-b { background: var(--accent-two); }
.visual-stage {
  display: grid;
  place-items: center;
  min-height: 326px;
  margin-top: 15px;
  padding: 18px 10px 10px;
  border: 1px solid var(--line);
  background: #f0f2ed;
}
.plot-figure { width: 100%; margin: 0; }
.plot-svg { display: block; width: 100%; height: auto; overflow: visible; }
.plot-axis { stroke: var(--line-strong); stroke-width: 1.5; }
.plot-grid-line { stroke: var(--line); stroke-width: 1; stroke-dasharray: 3 5; }
.plot-scale-label,
.plot-lane-label { fill: var(--muted); font-size: 11px; }
.plot-lane-label { font-weight: 760; }
.plot-band-a { fill: rgba(36, 91, 73, .12); }
.plot-band-b { fill: rgba(163, 107, 53, .14); }
.plot-mean-a,
.plot-mean-b { stroke-width: 2.5; }
.plot-mean-a { stroke: var(--accent); }
.plot-mean-b { stroke: var(--accent-two); }
.plot-sd-a,
.plot-sd-b { stroke-width: 1.3; stroke-dasharray: 5 4; }
.plot-sd-a { stroke: var(--accent); }
.plot-sd-b { stroke: var(--accent-two); }
.plot-point-a,
.plot-point-b { stroke: #fff; stroke-width: 1.6; }
.plot-point-a { fill: var(--accent); }
.plot-point-b { fill: var(--accent-two); }
.plot-label-a,
.plot-label-b { font-size: 11px; font-weight: 760; }
.plot-label-a { fill: var(--accent); }
.plot-label-b { fill: var(--accent-two); }
.visual-caption,
.visual-description,
.scale-note { color: var(--muted); font-size: .78rem; line-height: 1.55; }
.visual-caption { margin: 9px 0 0; text-align: center; }
.visual-description { margin: 11px 0 0; font-size: .84rem; }
.scale-note { margin: 7px 0 0; font-size: .74rem; }

.content-section { margin-top: 44px; }
.formula-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: 16px;
  border-top: 1px solid var(--line);
  border-left: 1px solid var(--line);
}
.formula-list article {
  display: grid;
  gap: 5px;
  min-width: 0;
  padding: 14px 15px;
  border-right: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}
.formula-list strong { overflow-wrap: anywhere; font-family: var(--symbol-font); font-size: .88rem; }
.formula-list span { color: var(--muted); font-size: .82rem; line-height: 1.55; }
.proof-guide {
  margin-top: 20px;
  padding: 16px 18px;
  border: 1px solid var(--line);
  background: var(--surface);
}
.proof-guide h3 { margin: 0; font-size: 1rem; }
.proof-guide ul { margin: 10px 0 0; padding-left: 1.25em; }
.proof-guide li { margin-top: 5px; overflow-wrap: anywhere; }
.proof-guide a { color: var(--accent); text-underline-offset: 3px; }
.example-box {
  margin-top: 18px;
  padding: 14px 16px;
  border-left: 3px solid var(--accent-two);
  background: var(--accent-two-soft);
}
.example-box h3 { margin: 0; font-size: .98rem; }
.example-box p { margin: 6px 0 0; overflow-wrap: anywhere; font-size: .86rem; }

@media (max-width: 1000px) {
  .tool-shell { grid-template-columns: 1fr; }
  .calculator-panel { border-right: 0; border-bottom: 1px solid var(--line); }
}
@media (max-width: 700px) {
  .series-results { grid-template-columns: 1fr; }
  .formula-list { grid-template-columns: 1fr; }
}
@media (max-width: 560px) {
  .calculator-panel, .visual-panel { padding: 19px 14px; }
  .result-details { grid-template-columns: 1fr; }
  .result-details .detail-wide { grid-column: auto; }
  .comparison-details { grid-template-columns: 1fr; }
  .form-actions { display: grid; grid-template-columns: 1fr; }
  .button { width: 100%; }
  .visual-stage { min-height: 278px; padding-inline: 5px; }
}