:root {
  color-scheme: light;
  --paper: #f5f4ef;
  --surface: #fbfaf6;
  --ink: #222824;
  --muted: #687069;
  --line: #cfd3cc;
  --line-strong: #9fa79f;
  --accent: #245b49;
  --accent-soft: #e2ebe5;
  --accent-strong: #173f32;
  --liquid: #2f7086;
  --liquid-soft: #dcebf0;
  --danger: #9b2f2f;
  --danger-soft: #f8e9e7;
  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; }
button, input, select { font: inherit; }
a { color: inherit; }
:focus-visible { outline: 3px solid var(--accent); 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 { margin: 0; font-size: clamp(1.2rem, 2vw, 1.48rem); line-height: 1.35; }
.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); }
.mode-fieldset, .values-fieldset { margin: 17px 0 0; padding: 0; border: 0; }
.mode-fieldset legend, .values-fieldset legend { margin-bottom: 8px; font-weight: 760; }
.values-fieldset { margin-top: 20px; }
.mode-options { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 6px; }
.mode-option { position: relative; display: block; cursor: pointer; }
.mode-option input { position: absolute; opacity: 0; }
.mode-option span { min-height: 48px; display: grid; place-items: center; padding: 7px 8px; border: 1px solid var(--line); background: var(--surface); color: var(--muted); text-align: center; font-size: .87rem; font-weight: 700; line-height: 1.35; }
.mode-option input:checked + span { border-color: var(--accent); background: var(--accent-soft); color: var(--accent); }
.mode-option input:focus-visible + span { outline: 3px solid var(--accent); outline-offset: 2px; }
.input-grid { display: grid; gap: 14px; }
.input-row label, .output-unit-row label { display: block; margin-bottom: 5px; font-weight: 720; }
.input-wrap { display: grid; grid-template-columns: minmax(0, 1fr) minmax(104px, .42fr); align-items: stretch; gap: 6px; }
.input-wrap input, .input-wrap select, .output-unit-row select { width: 100%; min-width: 0; min-height: 44px; border: 1px solid var(--line-strong); border-radius: 2px; padding: 9px 10px; color: var(--ink); background: var(--surface); }
.input-wrap input[aria-invalid="true"] { border-color: var(--danger); background: #fff8f8; }
.field-help { margin: 4px 0 0; color: var(--muted); font-size: .78rem; }
.field-error { min-height: 1.25em; margin: 2px 0 0; color: var(--danger); font-size: .82rem; }
.output-unit-row { margin-top: 15px; }
.form-error { margin: 12px 0 0; padding: 8px 10px; border-left: 4px solid var(--danger); background: var(--danger-soft); color: #762525; }
.form-error[hidden] { display: none; }
.form-actions { display: flex; gap: 8px; margin-top: 17px; }
.button { min-height: 42px; 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: var(--accent-strong); }
.button-secondary { background: var(--surface); color: var(--accent); }
.button:hover:not(:disabled) { border-color: var(--ink); }
.result-box { margin-top: 20px; padding: 15px 16px; border: 1px solid var(--accent); border-left-width: 4px; background: var(--accent-soft); }
.result-box[data-state="error"] { border-color: var(--danger); background: var(--danger-soft); }
.result-label { margin: 0; color: var(--accent); font-size: .8rem; font-weight: 780; }
.result-box[data-state="error"] .result-label { color: var(--danger); }
.result-value { display: block; margin-top: 2px; font-size: clamp(1.45rem, 3.2vw, 2.05rem); line-height: 1.28; font-weight: 780; font-variant-numeric: tabular-nums; overflow-wrap: anywhere; }
.result-status { margin: 5px 0 0; color: #3f4c46; font-size: .9rem; overflow-wrap: anywhere; }
.result-details { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); margin: 14px 0 0; border-top: 1px solid rgba(36, 91, 73, .35); border-left: 1px solid rgba(36, 91, 73, .35); }
.result-details[hidden] { display: none; }
.result-details div { min-width: 0; padding: 9px 10px; border-right: 1px solid rgba(36, 91, 73, .35); border-bottom: 1px solid rgba(36, 91, 73, .35); }
.result-details .detail-wide { grid-column: 1 / -1; }
.result-details dt { color: var(--muted); font-size: .76rem; font-weight: 760; }
.result-details dd { margin: 2px 0 0; font-size: .86rem; font-weight: 650; overflow-wrap: anywhere; }
.visual-heading-row { display: flex; justify-content: space-between; align-items: flex-start; gap: 14px; }
.status-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"] { border-color: var(--accent); background: var(--accent-soft); color: var(--accent); }
.visual-metrics { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); margin: 15px 0 0; border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.visual-metrics div { min-width: 0; padding: 9px 10px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.visual-metrics dt { color: var(--muted); font-size: .75rem; font-weight: 750; }
.visual-metrics dd { margin: 2px 0 0; font-size: .85rem; font-weight: 700; overflow-wrap: anywhere; }
.visual-stage { min-height: 316px; display: grid; place-items: center; margin-top: 15px; padding: 24px 12px 18px; overflow: hidden; border: 1px solid var(--line-strong); background: linear-gradient(180deg, #fbfaf6 0%, #edf2f2 100%); }
.dilution-figure { width: 100%; max-width: 490px; margin: 0; display: grid; grid-template-columns: minmax(105px, 1fr) 40px minmax(135px, 1.25fr); grid-template-rows: minmax(190px, auto) auto auto; align-items: center; justify-items: center; gap: 10px; }
.solution-vessel { position: relative; align-self: end; width: 100%; max-width: 175px; height: 165px; border: 3px solid var(--accent); border-radius: 6px 6px 13px 13px; background: rgba(220, 235, 240, .42); overflow: hidden; }
.final-vessel { height: 198px; max-width: 215px; }
.liquid { position: absolute; right: 5px; bottom: 5px; left: 5px; height: 57%; border-radius: 3px 3px 8px 8px; background: var(--liquid-soft); border-top: 3px solid var(--liquid); }
.liquid-final { height: 75%; background: #d4e7e5; border-top-color: var(--accent); }
.vessel-label { position: absolute; z-index: 2; top: 8px; left: 50%; padding: 1px 7px; border: 1px solid rgba(36,91,73,.45); background: rgba(251,250,246,.94); color: var(--accent-strong); font-size: .8rem; font-weight: 780; transform: translateX(-50%); }
.particle { position: absolute; z-index: 2; width: 10px; height: 10px; border: 2px solid #1f596b; border-radius: 50%; background: #8cc4d4; }
.p1 { left: 18%; bottom: 27%; } .p2 { left: 43%; bottom: 40%; } .p3 { left: 66%; bottom: 25%; } .p4 { left: 31%; bottom: 57%; } .p5 { left: 75%; bottom: 52%; }
.q1 { left: 16%; bottom: 30%; } .q2 { left: 35%; bottom: 47%; } .q3 { left: 54%; bottom: 25%; } .q4 { left: 73%; bottom: 42%; } .q5 { left: 25%; bottom: 64%; } .q6 { left: 46%; bottom: 63%; } .q7 { left: 65%; bottom: 59%; } .q8 { left: 82%; bottom: 66%; }
.transfer-arrow { color: var(--accent); font-size: 1.8rem; font-weight: 800; line-height: 1; }
.solvent-note { grid-column: 1 / 4; padding: 5px 10px; border: 1px dashed var(--line-strong); color: var(--muted); font-size: .82rem; text-align: center; }
.visual-caption { grid-column: 1 / 4; margin: 0; color: var(--muted); font-size: .82rem; text-align: center; overflow-wrap: anywhere; }
.visual-description { margin: 11px 0 0; color: #38413b; font-size: .9rem; }
.scale-note { margin: 7px 0 0; padding-left: 11px; border-left: 3px solid var(--line-strong); color: var(--muted); font-size: .78rem; }
.content-section { margin-top: 30px; padding-top: 25px; border-top: 1px solid var(--line-strong); }
.section-heading { margin-bottom: 15px; }
.formula-list { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.formula-list article { min-width: 0; display: grid; gap: 3px; padding: 12px 13px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); }
.formula-list strong { overflow-wrap: anywhere; }
.formula-list span { color: var(--muted); }
.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 { padding: 10px 13px 10px 30px; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); color: var(--muted); font-size: .86rem; }
.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); }
@media (max-width: 900px) { .tool-shell { grid-template-columns: 1fr; } .calculator-panel { border-right: 0; border-bottom: 1px solid var(--line); } .formula-list { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 600px) {
  .calculator-panel, .visual-panel { padding: 17px 14px; }
  .mode-options { grid-template-columns: 1fr; }
  .mode-option span { min-height: 43px; padding: 6px; font-size: .84rem; }
  .input-wrap { grid-template-columns: minmax(0, 1fr) 92px; }
  .form-actions { display: grid; grid-template-columns: 1fr; }
  .button { width: 100%; }
  .result-details { grid-template-columns: 1fr; }
  .result-details .detail-wide { grid-column: auto; }
  .visual-metrics { grid-template-columns: 1fr; }
  .visual-stage { min-height: 276px; padding-inline: 7px; }
  .dilution-figure { grid-template-columns: minmax(84px, 1fr) 25px minmax(105px, 1.25fr); gap: 6px; }
  .solution-vessel { height: 130px; min-width: 0; }
  .final-vessel { height: 155px; }
  .transfer-arrow { font-size: 1.35rem; }
  .formula-list { grid-template-columns: 1fr; }
  .proof-guide ul { grid-template-columns: 1fr; }
  .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); }
  .proof-guide li:last-child { border-bottom: 0; }
}
@media (prefers-reduced-motion: reduce) { html { scroll-behavior: auto; } *, *::before, *::after { scroll-behavior: auto !important; transition-duration: .01ms !important; animation-duration: .01ms !important; } }