.steam-layout {
    display: grid;
    grid-template-columns: minmax(320px, 0.85fr) minmax(0, 1.15fr);
    gap: 24px;
    align-items: start;
}

.steam-header-content {
    align-items: center;
}

.steam-header-content .header-right {
    margin-left: auto;
}

.steam-panel {
    display: grid;
    gap: 20px;
}

.steam-layout,
.steam-panel,
.input-section,
.output-section,
.section-card,
.trace-block,
.sidebar {
    min-width: 0;
}

.sidebar {
    display: grid;
    gap: 16px;
    align-content: start;
}

.panel-actions,
.button-row,
.unit-row {
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
    align-items: center;
}

.action-menu {
    position: relative;
}

.action-summary {
    list-style: none;
    gap: 8px;
}

.action-summary::-webkit-details-marker {
    display: none;
}

.action-summary::after {
    content: '+';
    color: var(--accent-engineering);
    font: 800 0.85rem 'JetBrains Mono', monospace;
}

.action-menu[open] > .action-summary::after {
    content: '-';
}

.action-menu-panel {
    position: absolute;
    top: calc(100% + 8px);
    right: 0;
    z-index: 20;
    display: grid;
    gap: 8px;
    min-width: 180px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-card);
    box-shadow: 0 12px 30px rgba(0, 0, 0, 0.18);
    padding: 10px;
}

.action-menu-panel .tool-btn {
    width: 100%;
    justify-content: flex-start;
}

.status-banner {
    border: 1px solid var(--border-color);
    background: var(--bg-card);
    color: var(--text-secondary);
    border-radius: 8px;
    padding: 10px 12px;
    font-size: 0.875rem;
}

.status-banner.error {
    border-color: rgba(239, 68, 68, 0.45);
    background: var(--accent-error-dim);
    color: var(--text-primary);
}

.input-section,
.output-section {
    display: grid;
    gap: 16px;
}

.section-card {
    border: 1px solid var(--border-color);
    background: var(--bg-card);
    border-radius: 8px;
    padding: 18px;
}

.section-card h3 {
    margin-bottom: 12px;
}

.foldable-card {
    display: block;
}

.foldable-summary {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
    cursor: pointer;
    list-style: none;
}

.foldable-summary::-webkit-details-marker {
    display: none;
}

.foldable-summary::after {
    content: '+';
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-width: 24px;
    min-height: 24px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    color: var(--accent-engineering);
    font: 800 0.9rem 'JetBrains Mono', monospace;
}

.foldable-card[open] > .foldable-summary::after {
    content: '-';
}

.foldable-summary h3 {
    margin-bottom: 0;
}

.foldable-content {
    display: grid;
    gap: 10px;
    margin-top: 12px;
}

.input-line {
    display: grid;
    gap: 6px;
}

.input-line span {
    color: var(--text-secondary);
    font-size: 0.84rem;
}

.input-line em {
    color: var(--text-muted);
    font-style: normal;
}

.main-select,
.main-input {
    width: 100%;
    min-height: 44px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-input);
    color: var(--text-primary);
    padding: 9px 10px;
    font: 500 0.9rem 'JetBrains Mono', monospace;
}

.main-select:focus,
.main-input:focus {
    outline: none;
    border-color: var(--accent-engineering);
    box-shadow: 0 0 0 3px var(--accent-engineering-dim);
}

.control-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
}

.field-stack {
    display: grid;
    gap: 12px;
}

.tool-btn {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    min-height: 44px;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-secondary);
    color: var(--text-primary);
    padding: 8px 12px;
    font: 600 0.84rem 'Space Grotesk', sans-serif;
    cursor: pointer;
    transition: border-color 0.15s ease, background 0.15s ease;
}

.tool-btn:hover:not(:disabled) {
    border-color: var(--accent-engineering);
    background: var(--bg-card-hover);
}

.tool-btn.primary {
    border-color: rgba(245, 158, 11, 0.55);
    background: var(--accent-engineering-dim);
}

.tool-btn:disabled {
    opacity: 0.55;
    cursor: wait;
}

.result-header {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    align-items: center;
    margin-bottom: 12px;
}

.result-kicker,
.property-unit,
.trace-note,
.empty-state,
.test-description,
.test-detail {
    color: var(--text-muted);
    font-size: 0.78rem;
}

.phase-chip {
    border: 1px solid var(--border-color);
    border-radius: 999px;
    padding: 5px 9px;
    font-size: 0.78rem;
    font-weight: 700;
    white-space: nowrap;
}

.phase-chip.compressed-liquid,
.phase-chip.saturated-liquid {
    border-color: rgba(6, 182, 212, 0.45);
    background: rgba(6, 182, 212, 0.12);
}

.phase-chip.superheated-vapor,
.phase-chip.saturated-vapor {
    border-color: rgba(139, 92, 246, 0.4);
    background: rgba(139, 92, 246, 0.12);
}

.phase-chip.supercritical-fluid {
    border-color: rgba(244, 63, 94, 0.4);
    background: rgba(244, 63, 94, 0.12);
}

.phase-chip.two-phase {
    border-color: rgba(34, 197, 94, 0.45);
    background: rgba(34, 197, 94, 0.12);
}

.property-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 10px;
}

.property-row {
    display: flex;
    justify-content: space-between;
    gap: 12px;
    align-items: center;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 10px 12px;
    background: var(--bg-secondary);
}

.property-label {
    font-weight: 700;
    font-size: 0.86rem;
}

.property-value {
    min-height: 44px;
    min-width: 44px;
    border: 0;
    background: transparent;
    color: var(--text-primary);
    font: 700 0.88rem 'JetBrains Mono', monospace;
    text-align: right;
    cursor: pointer;
}

.property-value.copy-success {
    color: var(--accent-success);
}

.warning-list {
    display: grid;
    gap: 8px;
    margin-bottom: 12px;
}

.warning-item {
    border: 1px solid rgba(234, 179, 8, 0.45);
    background: var(--accent-warning-dim);
    border-radius: 8px;
    padding: 9px 10px;
    color: var(--text-primary);
    font-size: 0.84rem;
}

.trace-table-wrap {
    overflow-x: auto;
    max-width: 100%;
    border: 1px solid var(--border-color);
    border-radius: 8px;
}

.trace-table {
    width: 100%;
    border-collapse: collapse;
    min-width: 620px;
    font: 500 0.78rem 'JetBrains Mono', monospace;
}

.trace-table th,
.trace-table td {
    padding: 8px 10px;
    border-bottom: 1px solid var(--border-color);
    text-align: right;
    white-space: nowrap;
}

.trace-table th {
    color: var(--text-secondary);
    background: var(--bg-secondary);
}

.trace-table th:first-child,
.trace-table td:first-child {
    text-align: left;
}

.trace-block-grid {
    display: grid;
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 12px;
}

.trace-block {
    display: grid;
    gap: 8px;
}

.candidate-list {
    display: grid;
    gap: 8px;
    margin-top: 12px;
}

.candidate-row {
    display: grid;
    grid-template-columns: auto 1fr auto;
    gap: 10px;
    align-items: center;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 9px 10px;
    background: var(--bg-secondary);
}

.candidate-index {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 24px;
    height: 24px;
    border-radius: 50%;
    background: var(--accent-engineering-dim);
    color: var(--accent-engineering);
    font-weight: 800;
}

.phase-context {
    display: grid;
    gap: 12px;
}

.phase-context-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 10px;
}

.phase-context-header > span:last-child,
.context-row span,
.context-meter span {
    color: var(--text-secondary);
    font-size: 0.78rem;
}

.context-grid,
.context-meters {
    display: grid;
    gap: 8px;
}

.context-row,
.context-meter {
    display: grid;
    gap: 6px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-secondary);
    padding: 9px 10px;
}

.context-row {
    grid-template-columns: minmax(0, 0.8fr) minmax(0, 1.2fr);
    align-items: center;
}

.context-row strong,
.context-meter strong {
    color: var(--text-primary);
    font: 700 0.84rem 'JetBrains Mono', monospace;
    text-align: right;
}

.context-meter > div:first-child {
    display: flex;
    justify-content: space-between;
    gap: 10px;
}

.context-meter-bar {
    display: block;
    width: 100%;
    height: 8px;
    border-radius: 999px;
    background: var(--bg-input);
    overflow: hidden;
}

.context-meter-bar::-webkit-meter-bar {
    border: 0;
    border-radius: 999px;
    background: var(--bg-input);
}

.context-meter-bar::-webkit-meter-optimum-value {
    border-radius: 999px;
    background: var(--accent-engineering);
}

.context-meter-bar::-moz-meter-bar {
    border-radius: 999px;
    background: var(--accent-engineering);
}

.comparison-pins {
    display: grid;
    gap: 10px;
    margin-bottom: 12px;
}

.comparison-card {
    display: grid;
    gap: 8px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 10px 12px;
    background: var(--bg-secondary);
}

.comparison-card.empty {
    border-style: dashed;
    color: var(--text-muted);
}

.comparison-card-header {
    display: flex;
    gap: 8px;
    align-items: center;
    justify-content: space-between;
}

.comparison-card > span,
.comparison-inputs,
.comparison-mini {
    color: var(--text-secondary);
    font-size: 0.78rem;
}

.comparison-inputs,
.comparison-mini {
    display: grid;
    gap: 4px;
}

.comparison-mini {
    font-family: 'JetBrains Mono', monospace;
}

.comparison-table-wrap {
    margin-top: 10px;
}

.comparison-table {
    min-width: 560px;
}

.chart-overlay-controls {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    align-items: center;
    padding: 10px 12px;
    margin-bottom: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-secondary);
    font-size: 0.78rem;
}

.chart-overlay-group {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 10px;
}

.chart-overlay-label {
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 0.06em;
    font-size: 0.68rem;
    font-weight: 600;
}

.chart-overlay-toggle {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    color: var(--text-secondary);
    cursor: pointer;
    user-select: none;
}

.chart-overlay-toggle input[type="checkbox"] {
    accent-color: var(--accent-engineering);
    cursor: pointer;
    margin: 0;
}

.chart-overlay-toggle:hover {
    color: var(--text-primary);
}

.chart-isobar-count {
    border: 1px solid var(--border-color);
    background: var(--bg-card);
    color: var(--text-secondary);
    font: 600 0.78rem 'JetBrains Mono', monospace;
    padding: 3px 10px;
    border-radius: 6px;
    cursor: pointer;
    min-width: 32px;
}

.chart-isobar-count:hover {
    color: var(--text-primary);
    border-color: var(--text-muted);
}

.chart-isobar-count.active {
    background: var(--accent-engineering);
    color: var(--bg-primary);
    border-color: var(--accent-engineering);
}

.chart-stack {
    display: grid;
    gap: 12px;
}

.chart-block {
    display: grid;
    gap: 10px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-secondary);
    padding: 10px;
}

.chart-header {
    display: flex;
    justify-content: space-between;
    gap: 10px;
    align-items: baseline;
}

.chart-header strong {
    font-size: 0.9rem;
}

.chart-header span {
    color: var(--text-muted);
    font-size: 0.76rem;
    text-align: right;
}

.steam-chart {
    display: block;
    width: 100%;
    height: auto;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-card);
}

.chart-grid line {
    stroke: var(--border-color);
    stroke-width: 1;
    opacity: 0.28;
}

.chart-axis line {
    stroke: var(--text-muted);
    stroke-width: 1.2;
}

.chart-axis text,
.chart-axis-labels text {
    fill: var(--text-muted);
    font: 600 0.62rem 'JetBrains Mono', monospace;
}

.chart-axis-labels text {
    fill: var(--text-secondary);
    font-size: 0.66rem;
}

.chart-dome-fill {
    fill: rgba(34, 197, 94, 0.08);
    stroke: none;
}

.chart-dome-line,
.chart-saturation-line,
.chart-isobar-line {
    fill: none;
    stroke: var(--accent-engineering);
    stroke-linecap: round;
    stroke-linejoin: round;
}

.chart-dome-line,
.chart-saturation-line {
    stroke-width: 2.6;
}

.chart-dome-line.liquid {
    stroke: rgb(6, 182, 212);
}

.chart-dome-line.vapor {
    stroke: rgb(139, 92, 246);
}

.chart-saturation-line {
    stroke: rgb(14, 165, 233);
}

/* Isobars recede behind the dome: thinner, dashed (longer pattern than
   quality curves to stay distinguishable), slightly muted. */
.chart-isobar-line {
    stroke-width: 1.3;
    stroke-dasharray: 7 4;
    opacity: 0.7;
    cursor: pointer;
}

.chart-isobar-line:hover,
.chart-isobar-line:focus,
.chart-isobar-line.hovered,
.chart-isobar-line.selected {
    opacity: 1;
    stroke-width: 2.4;
    stroke-dasharray: 0;
    outline: none;
}

.chart-isobar-line.isobar-0,
.chart-isobar-swatch.isobar-0 {
    stroke: rgb(14, 165, 233);
    background: rgb(14, 165, 233);
}

.chart-isobar-line.isobar-1,
.chart-isobar-swatch.isobar-1 {
    stroke: rgb(245, 158, 11);
    background: rgb(245, 158, 11);
}

.chart-isobar-line.isobar-2,
.chart-isobar-swatch.isobar-2 {
    stroke: rgb(34, 197, 94);
    background: rgb(34, 197, 94);
}

.chart-isobar-line.isobar-3,
.chart-isobar-swatch.isobar-3 {
    stroke: rgb(244, 63, 94);
    background: rgb(244, 63, 94);
}

/* Isotherms: solid strokes with warm-cool color ramp by temperature; the
   critical isotherm is dashed to read as a boundary. */
.chart-isotherm-line {
    fill: none;
    stroke-linecap: round;
    stroke-linejoin: round;
    stroke-width: 1.4;
    opacity: 0.85;
    cursor: pointer;
}

.chart-isotherm-line:hover,
.chart-isotherm-line:focus,
.chart-isotherm-line.hovered,
.chart-isotherm-line.selected {
    opacity: 1;
    stroke-width: 2.4;
    outline: none;
}

.chart-isotherm-line.isotherm-crit {
    stroke-dasharray: 6 4;
    stroke-width: 1.8;
}

.chart-isotherm-line.isotherm-0,
.chart-isotherm-swatch.isotherm-0 {
    stroke: rgb(56, 189, 248);
    background: rgb(56, 189, 248);
}

.chart-isotherm-line.isotherm-1,
.chart-isotherm-swatch.isotherm-1 {
    stroke: rgb(45, 212, 191);
    background: rgb(45, 212, 191);
}

.chart-isotherm-line.isotherm-2,
.chart-isotherm-swatch.isotherm-2 {
    stroke: rgb(250, 204, 21);
    background: rgb(250, 204, 21);
}

.chart-isotherm-line.isotherm-3,
.chart-isotherm-swatch.isotherm-3 {
    stroke: rgb(249, 115, 22);
    background: rgb(249, 115, 22);
}

.chart-isotherm-line.isotherm-4,
.chart-isotherm-swatch.isotherm-4 {
    stroke: rgb(220, 38, 38);
    background: rgb(220, 38, 38);
}

.chart-isotherm-line.isotherm-5,
.chart-isotherm-swatch.isotherm-5 {
    stroke: rgb(217, 70, 239);
    background: rgb(217, 70, 239);
}

.chart-quality-line {
    stroke: rgba(34, 197, 94, 0.9);
    stroke-width: 2;
    stroke-dasharray: 5 4;
}

.chart-quality-curve path {
    fill: none;
    stroke: rgba(139, 92, 246, 0.55);
    stroke-width: 1;
    stroke-dasharray: 3 3;
    pointer-events: none;
}

.chart-phase-regions path {
    /* Region tints sit behind everything except grid. Make sure they don't
       eat hover/click events meant for points, lines, or markers. */
    pointer-events: none;
}

.chart-phase-key {
    display: flex;
    flex-wrap: wrap;
    align-items: center;
    gap: 8px 14px;
    margin-top: 4px;
    color: var(--text-secondary);
    font-size: 0.72rem;
}

.chart-phase-key-item {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    white-space: nowrap;
}

.chart-phase-key-swatch {
    display: inline-block;
    width: 14px;
    height: 10px;
    border-radius: 3px;
    border: 1px solid var(--border-color);
    background: var(--bg-card);
}

/* Keep these alphas in sync with PHASE_COLORS in charts.js. */
.chart-phase-key-swatch.compressedLiquid,
.chart-phase-key-swatch.liquid {
    background: rgba(59, 130, 246, 0.5);
    border-color: rgba(59, 130, 246, 0.75);
}

.chart-phase-key-swatch.saturated {
    background: rgba(34, 197, 94, 0.35);
    border-color: rgba(34, 197, 94, 0.6);
}

.chart-phase-key-swatch.superheatedVapor,
.chart-phase-key-swatch.vapor {
    background: rgba(245, 158, 11, 0.35);
    border-color: rgba(245, 158, 11, 0.6);
}

.chart-phase-key-swatch.supercritical {
    background: rgba(244, 63, 94, 0.35);
    border-color: rgba(244, 63, 94, 0.6);
}

.chart-phase-key-swatch.solidNoData {
    background: rgba(148, 163, 184, 0.3);
    border-color: rgba(148, 163, 184, 0.55);
    /* Striped pattern hints that this region is conceptual, not actual data. */
    background-image: repeating-linear-gradient(45deg, rgba(0, 0, 0, 0.18) 0 2px, transparent 2px 4px);
}

.chart-stack-footnote {
    margin-top: 14px;
    padding: 10px 12px;
    border-radius: 8px;
    background: var(--bg-secondary);
    border: 1px dashed var(--border-color);
    color: var(--text-secondary);
    font-size: 0.74rem;
    line-height: 1.45;
}

.chart-quality-curve .chart-quality-label {
    fill: rgba(139, 92, 246, 0.95);
    font: 600 0.56rem 'JetBrains Mono', monospace;
    pointer-events: none;
    paint-order: stroke;
    stroke: var(--bg-card);
    stroke-width: 3px;
    stroke-linejoin: round;
}

.chart-hover-point {
    fill: transparent;
    stroke: transparent;
    stroke-width: 1.5;
    cursor: crosshair;
    pointer-events: all;
}

/* Subtle ring on hover/select — no bright fill, so a moving cursor doesn't
   light up the chart with blobs. */
.chart-hover-point:hover,
.chart-hover-point.hovered,
.chart-hover-point.selected {
    fill: var(--bg-card);
    stroke: var(--accent-engineering);
}

.chart-hover-point.isobar-0:hover,
.chart-hover-point.isobar-0.hovered,
.chart-hover-point.isobar-0.selected {
    stroke: rgb(14, 165, 233);
}

.chart-hover-point.isobar-1:hover,
.chart-hover-point.isobar-1.hovered,
.chart-hover-point.isobar-1.selected {
    stroke: rgb(245, 158, 11);
}

.chart-hover-point.isobar-2:hover,
.chart-hover-point.isobar-2.hovered,
.chart-hover-point.isobar-2.selected {
    stroke: rgb(34, 197, 94);
}

.chart-hover-point.isobar-3:hover,
.chart-hover-point.isobar-3.hovered,
.chart-hover-point.isobar-3.selected {
    stroke: rgb(244, 63, 94);
}

.chart-cp-glyph {
    cursor: pointer;
}

.chart-cp-glyph .chart-cp-diamond {
    fill: var(--accent-warning, #f59e0b);
    stroke: var(--bg-card);
    stroke-width: 1.5;
}

.chart-cp-glyph:hover .chart-cp-diamond,
.chart-cp-glyph:focus .chart-cp-diamond,
.chart-cp-glyph.hovered .chart-cp-diamond,
.chart-cp-glyph.selected .chart-cp-diamond {
    stroke-width: 3;
}

.chart-cp-glyph .chart-cp-label,
.chart-tp-glyph .chart-tp-label {
    fill: var(--text-secondary);
    font: 700 0.62rem 'JetBrains Mono', monospace;
    pointer-events: none;
    /* Halo so the label reads against the dome, isobars, or quality curves
       it may sit on top of. */
    paint-order: stroke;
    stroke: var(--bg-card);
    stroke-width: 3px;
    stroke-linejoin: round;
}

.chart-cp-glyph:hover .chart-cp-label,
.chart-cp-glyph:focus .chart-cp-label,
.chart-cp-glyph.hovered .chart-cp-label,
.chart-cp-glyph.selected .chart-cp-label,
.chart-tp-glyph:hover .chart-tp-label,
.chart-tp-glyph:focus .chart-tp-label,
.chart-tp-glyph.hovered .chart-tp-label,
.chart-tp-glyph.selected .chart-tp-label {
    fill: var(--text-primary);
}

.chart-tp-glyph {
    cursor: pointer;
}

.chart-tp-glyph circle {
    fill: rgb(34, 197, 94);
    stroke: var(--bg-card);
    stroke-width: 1.5;
}

.chart-tp-glyph:hover circle,
.chart-tp-glyph:focus circle,
.chart-tp-glyph.hovered circle,
.chart-tp-glyph.selected circle {
    stroke-width: 3;
}

.chart-marker {
    stroke: var(--bg-card);
    stroke-width: 1.8;
    cursor: pointer;
}

.chart-marker:hover,
.chart-marker:focus,
.chart-marker.hovered,
.chart-marker.selected {
    stroke-width: 4;
    outline: none;
}

.chart-marker.liquid,
.chart-marker.compressed-liquid,
.chart-marker.saturated-liquid {
    stroke: rgb(6, 182, 212);
}

.chart-marker.vapor,
.chart-marker.superheated-vapor,
.chart-marker.saturated-vapor {
    stroke: rgb(139, 92, 246);
}

.chart-marker.two-phase,
.chart-marker.on-dome,
.chart-marker.saturation {
    stroke: rgb(34, 197, 94);
}

.chart-marker.supercritical-fluid {
    stroke: rgb(244, 63, 94);
}

.chart-marker.current,
.chart-legend-swatch.current {
    fill: var(--accent-engineering);
    background: var(--accent-engineering);
}

.chart-marker.state-a,
.chart-legend-swatch.state-a {
    fill: rgb(6, 182, 212);
    background: rgb(6, 182, 212);
}

.chart-marker.state-b,
.chart-legend-swatch.state-b {
    fill: rgb(139, 92, 246);
    background: rgb(139, 92, 246);
}

.chart-legend {
    display: grid;
    gap: 6px;
    color: var(--text-secondary);
    font-size: 0.76rem;
}

.chart-legend.muted {
    color: var(--text-muted);
}

.chart-isobar-legend,
.chart-isotherm-legend {
    display: grid;
    gap: 6px;
    color: var(--text-muted);
    font-size: 0.74rem;
}

.chart-isobar-legend > div,
.chart-isotherm-legend > div {
    display: flex;
    flex-wrap: wrap;
    gap: 6px;
}

.chart-legend-row {
    display: flex;
    align-items: flex-start;
    gap: 8px;
}

.chart-legend-row > :last-child {
    flex: 1 1 auto;
    min-width: 0;
}

.chart-legend-button,
.chart-isobar-button,
.chart-isotherm-button {
    width: 100%;
    border: 1px solid var(--border-color);
    border-radius: 6px;
    background: var(--bg-card);
    color: var(--text-secondary);
    cursor: pointer;
    font: inherit;
    text-align: left;
    padding: 7px 8px;
}

.chart-isobar-button,
.chart-isotherm-button {
    display: inline-flex;
    width: auto;
    align-items: center;
    gap: 6px;
    min-height: 32px;
}

.chart-legend-button:hover,
.chart-legend-button:focus,
.chart-legend-button.hovered,
.chart-legend-button.selected,
.chart-isobar-button:hover,
.chart-isobar-button:focus,
.chart-isobar-button.hovered,
.chart-isobar-button.selected,
.chart-isotherm-button:hover,
.chart-isotherm-button:focus,
.chart-isotherm-button.hovered,
.chart-isotherm-button.selected {
    border-color: var(--accent-engineering);
    background: var(--bg-card-hover);
    color: var(--text-primary);
    outline: none;
}

.chart-legend-swatch {
    width: 10px;
    height: 10px;
    border-radius: 50%;
    margin-top: 0.28em;
    box-sizing: border-box;
}

.chart-legend-swatch.saturated-liquid {
    border: 2px solid rgb(6, 182, 212);
}

.chart-legend-swatch.saturated-vapor {
    border: 2px solid rgb(139, 92, 246);
}

.chart-legend-phase-tag {
    display: inline-flex;
    align-items: center;
    justify-content: center;
    width: 18px;
    height: 18px;
    margin: 0 4px;
    border-radius: 4px;
    font: 700 0.7rem 'JetBrains Mono', monospace;
    background: var(--bg-card-hover);
    color: var(--text-primary);
    flex-shrink: 0;
}

.chart-legend-phase-tag.saturated-liquid {
    background: rgba(6, 182, 212, 0.18);
    color: rgb(6, 182, 212);
    border: 1px solid rgba(6, 182, 212, 0.55);
}

.chart-legend-phase-tag.saturated-vapor {
    background: rgba(139, 92, 246, 0.18);
    color: rgb(139, 92, 246);
    border: 1px solid rgba(139, 92, 246, 0.55);
}

.chart-isobar-swatch,
.chart-isotherm-swatch {
    width: 18px;
    height: 3px;
    border-radius: 999px;
}

.chart-isotherm-swatch.isotherm-crit {
    background-image: repeating-linear-gradient(90deg, currentColor 0 4px, transparent 4px 7px);
    background-color: transparent;
}

.chart-detail {
    /* Collapsed by default — kill the grid row entirely so chart-block's
       gap doesn't reserve space for an empty strip. */
    display: none;
}

.chart-detail.active {
    display: block;
    border: 1px solid rgba(245, 158, 11, 0.45);
    border-radius: 8px;
    background: var(--bg-card);
    color: var(--text-primary);
    padding: 8px 10px;
    font-size: 0.76rem;
}

.test-summary {
    display: flex;
    gap: 12px;
    align-items: center;
    border-radius: 8px;
    padding: 10px 12px;
    margin-bottom: 10px;
}

.test-summary.pass {
    border: 1px solid rgba(34, 197, 94, 0.4);
    background: var(--accent-success-dim);
}

.test-summary.fail {
    border: 1px solid rgba(239, 68, 68, 0.45);
    background: var(--accent-error-dim);
}

.test-list {
    display: grid;
    gap: 8px;
    max-height: 430px;
    overflow: auto;
}

.test-row {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-secondary);
}

.test-row summary {
    display: grid;
    grid-template-columns: 56px 1fr auto;
    gap: 10px;
    align-items: center;
    min-height: 44px;
    padding: 9px 10px;
    cursor: pointer;
    list-style: none;
}

.test-row summary::-webkit-details-marker {
    display: none;
}

.test-row summary::after {
    content: '+';
    color: var(--text-muted);
    font: 800 0.85rem 'JetBrains Mono', monospace;
}

.test-row[open] summary::after {
    content: '-';
}

.test-row.pass summary > span {
    color: var(--accent-success);
    font-weight: 800;
}

.test-row.fail summary > span {
    color: var(--accent-error);
    font-weight: 800;
}

.test-row strong {
    font-size: 0.86rem;
}

.test-description,
.test-detail {
    margin: 0;
    padding: 0 10px 10px 76px;
}

.test-description {
    color: var(--text-secondary);
}

.empty-state,
.error-state {
    border: 1px dashed var(--border-color);
    border-radius: 8px;
    padding: 14px;
}

.empty-state.compact {
    padding: 8px;
}

.error-state {
    border-color: rgba(239, 68, 68, 0.45);
    background: var(--accent-error-dim);
    color: var(--text-primary);
}

.license-modal {
    max-width: 760px;
    width: calc(100% - 32px);
    max-height: calc(100vh - 48px);
    overflow: auto;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    background: var(--bg-card);
    color: var(--text-primary);
    padding: 20px;
}

.license-modal::backdrop {
    background: rgba(0, 0, 0, 0.62);
}

.license-modal h3 {
    margin-top: 18px;
    margin-bottom: 8px;
    font-size: 0.95rem;
}

.license-list {
    margin: 0 0 8px 18px;
    padding: 0;
    color: var(--text-secondary);
    font-size: 0.875rem;
    line-height: 1.55;
}

.license-notice {
    margin-top: 12px;
    border: 1px solid var(--border-color);
    border-radius: 8px;
    padding: 10px 12px;
}

.license-notice summary {
    cursor: pointer;
    color: var(--text-primary);
    font-size: 0.875rem;
    font-weight: 700;
}

.license-modal pre {
    max-height: 360px;
    overflow: auto;
    white-space: pre-wrap;
    color: var(--text-secondary);
    font: 500 0.78rem 'JetBrains Mono', monospace;
}

@media (max-width: 768px) {
    .steam-layout,
    .trace-block-grid,
    .property-grid,
    .control-grid {
        grid-template-columns: 1fr;
    }
}

@media (max-width: 480px) {
    .steam-header-content {
        flex-wrap: nowrap;
        align-items: center;
    }

    .steam-header-content .back-link {
        padding-left: 0;
    }

    .section-card {
        padding: 14px;
    }

    .panel-actions,
    .button-row {
        width: 100%;
    }

    .tool-btn,
    .action-menu,
    .action-summary {
        flex: 1 1 100%;
        width: 100%;
    }

    .action-menu-panel {
        position: static;
        margin-top: 8px;
    }

    .property-row,
    .candidate-row,
    .comparison-card-header,
    .context-row {
        grid-template-columns: 1fr;
    }

    .comparison-card-header,
    .phase-context-header {
        display: grid;
        align-items: start;
    }

    .context-row strong {
        text-align: left;
    }

    .property-row {
        align-items: flex-start;
    }

    .property-value {
        width: 100%;
        text-align: left;
    }
}