:root {
  color-scheme: light;
  --paper: #f5f4ef;
  --surface: #fbfaf6;
  --ink: #222824;
  --muted: #687069;
  --line: #cfd3cc;
  --line-strong: #9fa79f;
  --accent: #245b49;
  --accent-soft: #e2ebe5;
  --warm: #b56032;
  --warm-soft: #f4e5d9;
  --danger: #9b2f2f;
  --symbol-font: "Segoe UI Symbol", "Noto Sans Symbols 2", "Noto Sans Symbols", "DejaVu Sans", "Arial Unicode MS", sans-serif;
  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; }
html { scroll-behavior: smooth; }
body { margin: 0; color: var(--ink); background: var(--paper); line-height: 1.65; overflow-x: hidden; }
button, input, select { font: inherit; }
a { color: inherit; }
:focus-visible { outline: 3px solid #d88b22; outline-offset: 3px; }

.eyebrow, .section-kicker { margin: 0 0 5px; color: var(--accent); font-size: .78rem; font-weight: 780; letter-spacing: .08em; text-transform: uppercase; }
h2, h3, h4 { line-height: 1.35; }
h2 { margin: 0; font-size: clamp(1.2rem, 2vw, 1.48rem); }
h3 { margin: 0; font-size: 1rem; }
h4 { margin: 18px 0 9px; color: var(--muted); font-size: .84rem; letter-spacing: .03em; }

.tool-shell { display: grid; grid-template-columns: minmax(320px, .86fr) minmax(0, 1.14fr); border: 1px solid var(--line-strong); background: var(--surface); }
.calculator-panel, .result-panel { min-width: 0; padding: 24px; }
.calculator-panel { border-right: 1px solid var(--line); }
.calculator-panel form { display: grid; gap: 18px; }
.section-heading { margin-bottom: 2px; }

.input-grid { display: grid; gap: 14px; min-width: 0; }
.input-row { min-width: 0; }
.input-row-wide { padding-top: 1px; }
.input-row label:not(.visually-hidden) { display: block; margin-bottom: 5px; font-weight: 760; }
.input-wrap { display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: stretch; min-width: 0; }
.input-wrap input { width: 100%; min-width: 0; min-height: 46px; border: 1px solid var(--line-strong); padding: 9px 11px; color: var(--ink); background: var(--surface); font-variant-numeric: tabular-nums; }
.input-wrap input[aria-invalid="true"] { border-color: var(--danger); background: #fff8f8; }
.unit-static { min-width: 64px; display: grid; place-items: center; border: 1px solid var(--line-strong); border-left: 0; padding: 0 10px; color: var(--ink); background: var(--paper); font-family: var(--symbol-font); font-weight: 760; }
.help-text, .form-error, .scope-card p, .result-summary, .meaning-text, .curve-empty, .particle-figure figcaption { margin: 5px 0 0; color: var(--muted); font-size: .8rem; line-height: 1.55; overflow-wrap: anywhere; }
.form-error { margin-top: 0; padding: 9px 11px; border-left: 4px solid var(--danger); background: #f8e9e7; color: #762525; font-weight: 700; }
.button-row { display: flex; flex-wrap: wrap; gap: 8px; }
.button { min-height: 44px; border: 1px solid var(--accent); border-radius: 2px; padding: 8px 15px; cursor: pointer; font-weight: 760; }
.button-primary { background: var(--accent); color: #fff; }
.button-primary:hover { background: #1b4738; }
.button-quiet { background: var(--surface); color: var(--accent); }
.button:hover:not(:disabled) { border-color: var(--ink); }

.scope-card { display: grid; gap: 9px; margin-top: 23px; padding-top: 18px; border-top: 1px solid var(--line); }
.formula-line { margin: 0; padding: 10px 12px; border: 1px solid var(--line); background: #f7faf8; color: var(--ink); font-family: "Cambria Math", "Times New Roman", serif; font-size: 1.16rem; text-align: center; }
.scope-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0; margin: 0; padding: 0; border-top: 1px solid var(--line); border-left: 1px solid var(--line); list-style: none; }
.scope-list li { display: grid; gap: 1px; min-width: 0; padding: 8px 9px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.scope-list strong { font-family: var(--symbol-font); font-size: .8rem; overflow-wrap: anywhere; }
.scope-list span { color: var(--muted); font-size: .72rem; }

.result-panel { background: var(--surface); }
.result-heading-row, .visual-heading-row { display: flex; align-items: flex-start; justify-content: space-between; gap: 13px; min-width: 0; }
.status-badge, .phase-badge { flex: 0 0 auto; padding: 3px 8px; border: 1px solid var(--line-strong); background: var(--paper); color: var(--muted); font-size: .75rem; font-weight: 760; }
.status-badge[data-state="ready"], .status-badge[data-state="boundary"], .phase-badge[data-state="ready"] { border-color: var(--accent); background: var(--accent-soft); color: var(--accent); }
.status-badge[data-state="invalid"] { border-color: var(--danger); background: #f8e9e7; color: var(--danger); }
.status-badge[data-state="waiting"] { color: var(--muted); }
.result-summary { min-height: 2.6em; margin-top: 12px; }
.metric-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 8px; margin: 16px 0 0; }
.metric { min-width: 0; padding: 10px 11px; border: 1px solid var(--line); background: #fff; }
.metric-emphasis { border-color: var(--accent); background: var(--accent-soft); }
.metric dt { color: var(--muted); font-size: .74rem; font-weight: 760; }
.metric dd { min-height: 1.45em; margin: 2px 0 0; color: var(--ink); font-family: var(--symbol-font); font-size: 1rem; font-weight: 780; line-height: 1.35; overflow-wrap: anywhere; }
.metric-emphasis dd { color: var(--accent); font-size: 1.2rem; }
.calculation-details { margin-top: 18px; padding-top: 15px; border-top: 1px solid var(--line); }
.details-list { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); margin: 10px 0 0; border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.details-list div { min-width: 0; padding: 8px 9px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.details-list dt { color: var(--muted); font-size: .72rem; font-weight: 760; }
.details-list dd { margin: 2px 0 0; font-family: var(--symbol-font); font-size: .8rem; font-weight: 700; overflow-wrap: anywhere; }
.energy-breakdown { display: grid; gap: 5px; margin: 0; padding-left: 21px; color: var(--ink); }
.energy-breakdown li { padding: 6px 8px; border-left: 3px solid var(--line-strong); background: #fff; font-family: var(--symbol-font); font-size: .78rem; overflow-wrap: anywhere; }
.energy-breakdown li[data-kind="latent"] { border-left-color: var(--warm); background: var(--warm-soft); }
.energy-breakdown li[data-kind="sensible"] { border-left-color: var(--accent); }
.meaning-text { padding: 9px 10px; border-left: 3px solid var(--accent); background: #f7faf8; }

.visual-card { margin-top: 20px; padding-top: 17px; border-top: 1px solid var(--line); }
.visual-subtitle { margin: 3px 0 0; color: var(--muted); font-size: .74rem; line-height: 1.45; }
.visual-heading-row output { flex: 0 0 auto; max-width: 47%; color: var(--accent); font-family: var(--symbol-font); font-size: .76rem; font-weight: 750; text-align: right; overflow-wrap: anywhere; }
#heat-curve { display: block; width: 100%; height: auto; margin-top: 12px; border: 1px solid var(--line-strong); background: var(--paper); }
.plot-background { fill: #fbfaf6; }
.grid-line { stroke: #dfe3dd; stroke-width: 1; }
.axis-line { stroke: #69736b; stroke-width: 1.2; }
.axis-tick, .axis-label { fill: var(--muted); font-family: var(--symbol-font); font-size: 11px; }
.axis-label { font-size: 12px; }
.curve-line { fill: none; stroke: var(--accent); stroke-width: 3; stroke-linejoin: round; stroke-linecap: round; }
.curve-marker { stroke: var(--warm); stroke-width: 1.4; stroke-dasharray: 4 4; }
.curve-marker-label { fill: var(--warm); font-family: var(--symbol-font); font-size: 10px; font-weight: 700; }
.current-guide { stroke: var(--accent); stroke-width: 1.2; stroke-dasharray: 2 3; opacity: .72; }
.current-point { fill: var(--warm); stroke: #fff; stroke-width: 2; }
.curve-empty { min-height: 1.5em; }

.particle-figure { margin: 12px 0 0; }
#particle-diagram { display: block; width: 100%; height: auto; border: 1px solid var(--line-strong); background: var(--paper); }
.particle-vessel { fill: #fbfaf6; stroke: #69736b; stroke-width: 1.2; }
.particle-waterline { stroke: #9ab8aa; stroke-width: 1; stroke-dasharray: 5 4; }
.particle-waterline-label { fill: #6c9583; font-family: var(--symbol-font); font-size: 10px; }
.particle { stroke: #fff; stroke-width: 1.2; }
.particle--ice { fill: #6b9fc7; }
.particle--water { fill: #2f8d83; }
.particle--steam { fill: #b56032; }
.particle-phase-label { fill: var(--ink); font-family: var(--symbol-font); font-size: 13px; font-weight: 760; }
.particle-figure figcaption { min-height: 2.8em; }

.content-section { margin-top: 30px; padding-top: 25px; border-top: 1px solid var(--line-strong); }
.steps-list { display: grid; grid-template-columns: repeat(4, 1fr); gap: 0; margin: 0; padding: 0; border-block: 1px solid var(--line); list-style: none; counter-reset: steps; }
.steps-list li { position: relative; min-width: 0; padding: 35px 12px 13px; border-right: 1px solid var(--line); counter-increment: steps; font-size: .86rem; overflow-wrap: anywhere; }
.steps-list li:last-child { border-right: 0; }
.steps-list li::before { content: counter(steps, decimal-leading-zero); position: absolute; top: 7px; left: 12px; color: var(--accent); font-size: .75rem; font-weight: 800; }
.formula-list { display: grid; grid-template-columns: repeat(4, 1fr); border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.formula-list div { display: grid; gap: 4px; min-width: 0; padding: 12px 13px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.formula-list strong { font-family: "Cambria Math", "Times New Roman", serif; font-size: 1rem; }
.formula-list span { color: var(--muted); font-size: .82rem; overflow-wrap: anywhere; }
.proof-guide { margin-top: 18px; border: 1px solid var(--line); }
.proof-guide h3 { margin: 0; padding: 10px 13px; border-bottom: 1px solid var(--line); color: var(--accent); font-size: .92rem; }
.proof-guide ul { display: grid; grid-template-columns: repeat(2, 1fr); margin: 0; padding: 0; list-style: none; }
.proof-guide li { min-width: 0; padding: 10px 13px 10px 30px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); color: var(--muted); font-size: .84rem; overflow-wrap: anywhere; }
.proof-guide li:nth-child(2n) { border-right: 0; }
.proof-guide li:nth-last-child(-n + 2) { border-bottom: 0; }
.proof-guide li::before { content: "—"; margin-left: -17px; margin-right: 7px; color: var(--accent); }

[hidden] { display: none !important; }
@media (max-width: 900px) {
  .tool-shell { grid-template-columns: 1fr; }
  .calculator-panel { border-right: 0; border-bottom: 1px solid var(--line); }
  .formula-list, .steps-list { grid-template-columns: repeat(2, 1fr); }
  .steps-list li { border-bottom: 1px solid var(--line); }
  .steps-list li:nth-child(2n) { border-right: 0; }
  .steps-list li:nth-last-child(-n + 2) { border-bottom: 0; }
}
@media (max-width: 600px) {
  .calculator-panel, .result-panel { padding: 17px 14px; }
  .scope-list, .metric-grid, .details-list, .formula-list, .steps-list, .proof-guide ul { grid-template-columns: 1fr; }
  .scope-list li, .steps-list li { border-right: 1px solid var(--line); }
  .scope-list li:last-child, .steps-list li:last-child { border-bottom: 1px solid var(--line); }
  .scope-list li:last-child, .steps-list li:last-child, .proof-guide li:last-child { border-bottom: 0; }
  .form-actions, .button-row { display: grid; grid-template-columns: 1fr; }
  .button { width: 100%; }
  .result-heading-row, .visual-heading-row { display: grid; }
  .visual-heading-row output { max-width: none; text-align: left; }
  .proof-guide li, .proof-guide li:nth-child(2n), .proof-guide li:nth-last-child(-n + 2) { border-right: 0; border-bottom: 1px solid var(--line); }
}
@media (max-width: 380px) {
  .unit-static { min-width: 54px; padding-inline: 7px; }
  .metric dd { font-size: .92rem; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; animation-iteration-count: 1 !important; }
}