:root {
  color-scheme: light;
  --bg: #f5f6f3;
  --surface: #ffffff;
  --surface-muted: #eef2ed;
  --ink: #17201f;
  --muted: #5a6663;
  --line: #d5ddd6;
  --accent: #176b63;
  --accent-strong: #0f4f49;
  --blue: #1f5f99;
  --warning: #9a5b00;
  --warning-bg: #fff7df;
  --danger: #9a3412;
  --danger-bg: #fff1eb;
  --ready: #166534;
  --positive: #1f7a4d;
  --negative: #8a3c2a;
  --sid: #1f5f99;
  --albumin: #9a5b00;
  --ui: #5b5570;
  --lactate: #8a3c2a;
  --residual-ui: #4f6b62;
  font-family:
    Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

body {
  margin: 0;
  min-height: 100svh;
  background: var(--bg);
  color: var(--ink);
}

button,
input,
select {
  font: inherit;
}

button,
select {
  cursor: pointer;
}

button:disabled,
select:disabled {
  cursor: not-allowed;
  opacity: 0.55;
}

.app-header,
.app-shell,
.site-footer {
  width: min(1220px, calc(100% - 32px));
  margin: 0 auto;
}

.app-header {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(220px, 320px);
  gap: 28px;
  align-items: end;
  padding: 42px 0 26px;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--accent);
  font-size: 0.78rem;
  font-weight: 800;
  letter-spacing: 0;
  text-transform: uppercase;
}

h1,
h2,
h3,
p {
  margin-top: 0;
}

h1 {
  max-width: 820px;
  margin-bottom: 14px;
  font-size: clamp(2.4rem, 6vw, 4.8rem);
  line-height: 0.98;
  letter-spacing: 0;
}

h2 {
  margin-bottom: 4px;
  font-size: 1.25rem;
  letter-spacing: 0;
}

h3 {
  margin-bottom: 14px;
  font-size: 1rem;
  letter-spacing: 0;
}

h4 {
  margin: 0 0 12px;
  font-size: 0.92rem;
  letter-spacing: 0;
}

.lede {
  max-width: 820px;
  margin-bottom: 0;
  color: var(--muted);
  font-size: 1.05rem;
  line-height: 1.6;
}

.header-links {
  margin: 16px 0 0;
  font-size: 0.95rem;
  font-weight: 800;
}

a {
  color: var(--accent-strong);
  text-decoration-thickness: 2px;
  text-underline-offset: 3px;
}

.runtime-card,
.input-panel,
.result-block {
  min-width: 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
}

.runtime-card {
  padding: 18px;
}

#runtime-status {
  margin-bottom: 12px;
  font-weight: 700;
  line-height: 1.4;
}

#runtime-status[data-state="loading"] {
  color: var(--accent);
}

#runtime-status[data-state="ready"] {
  color: var(--ready);
}

#runtime-status[data-state="error"] {
  color: var(--danger);
}

.app-shell {
  display: grid;
  grid-template-columns: minmax(320px, 0.92fr) minmax(0, 1.35fr);
  gap: 24px;
  align-items: start;
  padding-bottom: 36px;
}

.why-panel {
  display: grid;
  grid-column: 1 / -1;
  grid-template-columns: minmax(260px, 0.8fr) repeat(2, minmax(0, 1fr));
  gap: 24px;
  border-block: 1px solid var(--line);
  padding: 24px 0;
}

.why-panel h2 {
  max-width: 440px;
  margin-bottom: 0;
  font-size: clamp(1.35rem, 2.3vw, 2rem);
  line-height: 1.12;
}

.why-panel p {
  margin: 0;
  color: var(--muted);
  line-height: 1.6;
}

.input-panel {
  position: sticky;
  top: 16px;
  padding: 22px;
}

.section-heading {
  margin-bottom: 20px;
}

fieldset {
  margin: 0 0 20px;
  border: 0;
  border-top: 1px solid var(--line);
  padding: 18px 0 0;
}

legend {
  padding-right: 12px;
  color: var(--ink);
  font-weight: 800;
}

.field-grid,
.unit-row {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

label {
  display: grid;
  gap: 6px;
  color: var(--muted);
  font-size: 0.86rem;
  font-weight: 700;
}

label span {
  display: flex;
  justify-content: space-between;
  gap: 8px;
}

small {
  color: var(--muted);
  font-weight: 600;
}

input,
select {
  min-height: 42px;
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: #fff;
  color: var(--ink);
  padding: 9px 10px;
}

input:focus,
select:focus,
button:focus-visible {
  outline: 3px solid rgba(31, 95, 153, 0.26);
  outline-offset: 2px;
}

.checkbox-row {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
}

.checkbox-row input {
  min-height: auto;
  width: 18px;
  height: 18px;
}

.optional-field-grid {
  margin-bottom: 14px;
}

.toggle-stack {
  display: grid;
  gap: 10px;
}

.example-row {
  display: grid;
  gap: 8px;
  margin: 4px 0 16px;
}

.helper-text {
  margin: -2px 0 0;
  color: var(--muted);
  font-size: 0.84rem;
  line-height: 1.4;
}

.action-row {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}

button {
  min-height: 42px;
  border: 1px solid var(--accent);
  border-radius: 6px;
  background: var(--accent);
  color: #fff;
  padding: 9px 14px;
  font-weight: 800;
}

.secondary-button {
  border-color: var(--line);
  background: var(--surface-muted);
  color: var(--ink);
}

.message-list {
  margin: 14px 0 0;
  border-radius: 6px;
  padding: 12px 14px;
  font-size: 0.92rem;
  line-height: 1.45;
}

.message-list ul {
  margin: 0;
  padding-left: 20px;
}

.error-list {
  border: 1px solid #efb39e;
  background: var(--danger-bg);
  color: var(--danger);
}

.warning-list {
  border: 1px solid #efd48f;
  background: var(--warning-bg);
  color: var(--warning);
}

.output-panel {
  display: grid;
  gap: 16px;
  min-width: 0;
}

.result-block {
  padding: 20px;
}

.step-label {
  margin: 0 0 8px;
  color: var(--accent-strong);
  font-size: 0.78rem;
  font-weight: 900;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.step-headline {
  margin-top: 16px;
  border-top: 1px solid var(--line);
  padding-top: 16px;
}

.example-processes {
  margin-top: 16px;
}

.example-processes h4 {
  margin: 0 0 10px;
}

.comparison-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  margin-top: 18px;
}

.comparison-column {
  border-top: 1px solid var(--line);
  padding-top: 16px;
}

.compact-detail-list {
  margin-top: 14px;
}

.compact-note {
  margin: 16px 0 0;
  border-left: 4px solid var(--warning);
  background: var(--warning-bg);
  color: var(--warning);
  padding: 10px 12px;
  line-height: 1.5;
}

.comparison-extra {
  margin-top: 16px;
  border-top: 1px solid var(--line);
  padding-top: 14px;
}

.compact-result {
  display: grid;
  gap: 8px;
}

.metric-chip {
  display: inline-flex;
  width: fit-content;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface-muted);
  color: var(--ink);
  padding: 8px 10px;
  font-weight: 800;
}

.formula-list {
  display: grid;
  gap: 10px;
  margin: 16px 0 0;
  padding: 0;
  list-style: none;
  color: var(--muted);
  line-height: 1.55;
}

.formula-list li {
  border-left: 3px solid var(--line);
  padding-left: 12px;
}

.formula-list strong {
  color: var(--ink);
}

.formula-list code {
  color: var(--accent-strong);
  font-weight: 800;
}

details {
  margin-top: 14px;
}

summary {
  color: var(--accent);
  cursor: pointer;
  font-weight: 800;
}

.mini-gallery {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin: 14px 0;
}

.mini-schematic {
  margin: 0;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface-muted);
  padding: 10px;
}

.mini-schematic svg {
  display: block;
  width: 100%;
  height: auto;
}

.mini-schematic line {
  stroke: var(--ink);
  stroke-width: 2;
}

.mini-schematic rect {
  fill: color-mix(in srgb, var(--sid) 68%, white);
  stroke: rgba(23, 32, 31, 0.22);
}

.mini-schematic[data-mini-example="hypochloremic-alkalosis"] rect,
.mini-schematic[data-mini-example="offset"] rect:nth-of-type(2) {
  fill: color-mix(in srgb, var(--albumin) 68%, white);
}

.mini-schematic text {
  fill: var(--ink);
  font-size: 12px;
  font-weight: 800;
}

.mini-schematic figcaption {
  color: var(--muted);
  font-size: 0.84rem;
  font-weight: 800;
  line-height: 1.35;
}

.empty-state,
.body-copy,
.visual-summary {
  color: var(--muted);
  line-height: 1.6;
}

.detail-list {
  display: grid;
  grid-template-columns: minmax(140px, 0.75fr) minmax(0, 1.25fr);
  gap: 10px 16px;
  margin: 0;
}

.detail-list dt {
  color: var(--muted);
  font-weight: 800;
}

.detail-list dd {
  margin: 0;
  color: var(--ink);
}

#limitations-list,
#cautions-list,
.annotation-list {
  margin: 0 0 12px;
  padding-left: 20px;
  color: var(--muted);
  line-height: 1.55;
}

.visual-scroll {
  max-width: 100%;
  min-width: 0;
  overflow-x: auto;
  padding: 4px 0 8px;
  scrollbar-color: var(--line) transparent;
}

.partition-chart,
.teaching-diagram,
.compensation-map {
  min-width: 680px;
}

.visual-svg {
  display: block;
  width: 100%;
  height: auto;
}

.partition-svg,
.teaching-svg {
  overflow: visible;
}

.axis-line,
.grid-line,
.row-baseline {
  stroke: var(--line);
  stroke-width: 1;
}

.grid-line {
  stroke-dasharray: 4 5;
}

.zero-line {
  stroke: var(--ink);
  stroke-width: 2;
}

.axis-label,
.axis-unit,
.direction-label,
.row-label,
.partition-segment-label,
.total-label,
.anchor-label,
.sid-label,
.teaching-note,
.teaching-footnote,
.concept-slot text {
  fill: var(--ink);
  font-size: 13px;
  font-weight: 800;
}

.axis-label,
.axis-unit,
.direction-label,
.teaching-note,
.teaching-footnote {
  fill: var(--muted);
  font-weight: 700;
}

.row-label {
  fill: var(--muted);
}

.partition-segment-label {
  fill: var(--ink);
}

.partition-segment {
  stroke: rgba(23, 32, 31, 0.28);
  stroke-width: 1;
}

.segment-sbe-sid {
  fill: color-mix(in srgb, var(--sid) 76%, white);
}

.segment-sbe-alb {
  fill: color-mix(in srgb, var(--albumin) 70%, white);
}

.segment-sbe-ui {
  fill: color-mix(in srgb, var(--ui) 74%, white);
}

.segment-sbe-lactate {
  fill: color-mix(in srgb, var(--lactate) 72%, white);
}

.segment-sbe-ui-non-lactate {
  fill: color-mix(in srgb, var(--residual-ui) 76%, white);
}

.step-connector {
  stroke: var(--muted);
  stroke-width: 1.5;
  stroke-dasharray: 3 5;
}

.total-marker {
  stroke: var(--ink);
  stroke-width: 3;
}

.anchor-line,
.sid-bracket,
.map-guide {
  fill: none;
  stroke: var(--ink);
  stroke-width: 2;
}

.map-guide {
  stroke-width: 2;
}

.acute-guide {
  stroke: var(--muted);
}

.chronic-guide {
  stroke: var(--sid);
}

.metabolic-acidosis-guide {
  stroke: var(--negative);
}

.metabolic-alkalosis-guide {
  stroke: var(--positive);
}

.reference-tick {
  stroke: var(--warning);
  stroke-width: 2;
  stroke-dasharray: 5 4;
}

.anchor-dot {
  stroke: var(--ink);
  stroke-width: 2;
}

.sodium-dot {
  fill: color-mix(in srgb, var(--sid) 72%, white);
}

.chloride-dot {
  fill: color-mix(in srgb, var(--residual-ui) 72%, white);
}

.concept-slot rect {
  fill: var(--surface-muted);
  stroke: var(--line);
}

.concept-slot[data-concept="sid"] rect {
  fill: color-mix(in srgb, var(--sid) 14%, white);
}

.concept-slot[data-concept="albumin"] rect {
  fill: color-mix(in srgb, var(--albumin) 14%, white);
}

.concept-slot[data-concept="ui"] rect {
  fill: color-mix(in srgb, var(--ui) 12%, white);
}

.normal-point {
  fill: var(--surface);
  stroke: var(--ink);
  stroke-width: 2;
}

.patient-point {
  fill: var(--accent);
  stroke: var(--ink);
  stroke-width: 2;
}

.map-label {
  fill: var(--ink);
  font-size: 12px;
  font-weight: 800;
}

.site-footer {
  border-top: 1px solid var(--line);
  padding: 24px 0 36px;
  color: var(--muted);
  font-size: 0.92rem;
  line-height: 1.6;
}

.site-footer p {
  max-width: 920px;
  margin-bottom: 10px;
}

@media (max-width: 900px) {
  .app-header,
  .app-shell,
  .why-panel {
    grid-template-columns: 1fr;
  }

  .input-panel {
    position: static;
  }
}

@media (max-width: 560px) {
  .app-header,
  .app-shell,
  .site-footer {
    width: min(100% - 24px, 1220px);
  }

  .field-grid,
  .unit-row,
  .mini-gallery,
  .comparison-grid,
  .detail-list,
  .compact-detail-list {
    grid-template-columns: 1fr;
  }

  .partition-chart,
  .teaching-diagram,
  .compensation-map {
    min-width: 0;
  }
}