:root {
    color-scheme: light;
    --bg: #f3f4f8;
    --bg-alt: #e7e9f1;
    --surface: #ffffff;
    --surface-alt: #fdfdfd;
    --text: #1c1c22;
    --muted: #6f7787;
    --accent: #2563eb;
    --accent-strong: #0f172a;
    --accent-soft: rgba(37, 99, 235, 0.12);
    --accent-cyan: #0ea5e9;
    --field: #fefefe;
    --field-border: #cfd3df;
    --alert-info: #2563eb;
    --alert-success: #0ea5e9;
    --alert-warning: #d97706;
    --alert-error: #e11d48;
    --severity-info-bg: rgba(37, 99, 235, 0.08);
    --severity-warning-bg: rgba(217, 119, 6, 0.12);
    --severity-error-bg: rgba(225, 29, 72, 0.12);
}

[data-theme="dark"] {
    color-scheme: dark;
    --bg: #101522;
    --bg-alt: #151b2c;
    --surface: #1b2335;
    --surface-alt: #1f293d;
    --text: #f2f5ff;
    --muted: #a8b3cc;
    --accent: #60a5fa;
    --accent-strong: #dbeafe;
    --accent-soft: rgba(96, 165, 250, 0.2);
    --accent-cyan: #7dd3fc;
    --field: #1c2536;
    --field-border: #2e3a52;
    --alert-info: #60a5fa;
    --alert-success: #7dd3fc;
    --alert-warning: #facc15;
    --alert-error: #fb7185;
    --severity-info-bg: rgba(96, 165, 250, 0.18);
    --severity-warning-bg: rgba(250, 204, 21, 0.22);
    --severity-error-bg: rgba(251, 113, 133, 0.22);
}

*,
*::before,
*::after {
    box-sizing: border-box;
}

body {
    margin: 0;
    min-height: 100vh;
    font-family: 'Space Grotesk', system-ui, -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
    font-size: 1rem;
    background: linear-gradient(160deg, var(--bg), var(--bg-alt));
    color: var(--text);
    line-height: 1.5;
}

a {
    color: inherit;
}

.app-shell {
    min-height: 100vh;
    display: flex;
    flex-direction: column;
    padding: 0 3vw 2rem;
    gap: 1rem;
}

.top-bar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    height: 60px;
    border-bottom: 1px solid var(--field-border);
}

.brand-mark {
    display: inline-flex;
    align-items: center;
    gap: 0.7rem;
    text-decoration: none;
}

.brand-icon {
    width: 36px;
    height: 36px;
    border-radius: 8px;
    display: grid;
    place-items: center;
    background: var(--accent-soft);
    color: var(--accent);
    font-weight: 600;
}

.brand-copy {
    display: flex;
    flex-direction: column;
    text-transform: uppercase;
    letter-spacing: 0.08em;
    font-size: 0.75rem;
    color: var(--muted);
}

.brand-copy strong {
    letter-spacing: 0.02em;
    text-transform: none;
    color: var(--text);
    margin-bottom: 0.2rem;
    font-size: 1rem;
}

.top-nav {
    display: flex;
    align-items: center;
    gap: 0.8rem;
}

.top-nav a {
    text-decoration: none;
    font-weight: 600;
    padding: 0.3rem 0.7rem;
    border-radius: 6px;
    font-size: 0.95rem;
}

.top-nav a:hover {
    background: var(--accent-soft);
    color: var(--accent-strong);
}

.theme-toggle {
    border: 1px solid var(--field-border);
    border-radius: 999px;
    padding: 0.3rem 0.6rem;
    background: linear-gradient(90deg, var(--surface), var(--surface-alt));
    color: var(--text);
    display: flex;
    align-items: center;
    gap: 0.35rem;
    cursor: pointer;
    font-weight: 600;
    font-size: 0.9rem;
}

.theme-toggle::before {
    content: '☀︎';
    font-size: 0.95rem;
}

[data-theme="dark"] .theme-toggle::before {
    content: '☾';
}

.main-stage {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.hero {
    padding-top: 1.8rem;
    text-align: center;
    display: flex;
    flex-direction: column;
    gap: 0.4rem;
}

.hero h1 {
    margin: 0;
    font-size: clamp(2rem, 5vw, 3.2rem);
    letter-spacing: 0.02em;
    line-height: 1.2;
}

.hero-subtitle {
    text-transform: uppercase;
    letter-spacing: 0.25em;
    font-size: 0.78rem;
    color: var(--muted);
}

.hero-search {
    width: min(460px, 80vw);
    margin: 0 auto;
}

.hero-search input {
    width: 100%;
    border-radius: 999px;
    border: 1px solid var(--field-border);
    padding: 0.9rem 1.2rem;
    background: var(--field);
    color: var(--text);
    font-size: 1rem;
}

.tool-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 0.8rem;
}

.tool-tile {
    display: block;
    text-decoration: none;
    border: 1px solid var(--field-border);
    border-radius: 10px;
    background: var(--surface);
    padding: 1rem;
    min-height: 140px;
    transition: box-shadow 0.2s ease;
}

.tool-tile:hover {
    box-shadow: inset 0 0 18px rgba(96, 165, 250, 0.18);
}

.tool-tile--incoming {
    position: relative;
    pointer-events: none;
    border-style: dashed;
    opacity: 0.75;
    background: linear-gradient(135deg, var(--surface), var(--surface-alt));
    overflow: hidden;
}

.tool-tile--incoming::after {
    content: "";
    position: absolute;
    inset: 0;
    border-radius: 10px;
    background: linear-gradient(160deg, rgba(15, 23, 42, 0.08), rgba(59, 130, 246, 0.12));
    pointer-events: none;
    z-index: 0;
}

.tool-tile--incoming .tile-head,
.tool-tile--incoming p,
.tool-tile--incoming .tag-list,
.tool-tile--incoming .tag-list li {
    position: relative;
    z-index: 1;
}

.incoming-flag {
    position: absolute;
    top: 0.75rem;
    right: 0.75rem;
    z-index: 2;
    font-size: 0.75rem;
    text-transform: uppercase;
    letter-spacing: 0.12em;
    padding: 0.25rem 0.6rem;
    border-radius: 999px;
    background: var(--accent);
    color: #fff;
    font-weight: 700;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.25);
    z-index: 2;
}

.tile-head {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    font-size: 0.85rem;
    color: var(--muted);
}

.tile-head h2 {
    margin: 0;
    font-size: 1.05rem;
    color: var(--text);
}

.tool-tile p {
    margin: 0.4rem 0;
    color: var(--muted);
    font-size: 0.9rem;
}

.tag-list {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
    flex-wrap: wrap;
    gap: 0.35rem;
    font-size: 0.75rem;
}

.tag-list li {
    padding: 0.15rem 0.5rem;
    border: 1px solid var(--field-border);
    border-radius: 999px;
    background: var(--surface-alt);
    color: var(--muted);
    font-size: 0.75rem;
}

.explain-row {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1rem;
}

.explain-row article {
    border-top: 1px solid var(--field-border);
    padding-top: 0.8rem;
}

.workbench {
    display: flex;
    flex-direction: column;
    gap: 1.5rem;
}

.workbench-grid {
    display: grid;
    grid-template-columns: minmax(0, 1fr);
}

.editor-pane {
    background: var(--surface);
    border: 1px solid var(--field-border);
    border-radius: 12px;
}

.pane-toolbar {
    display: flex;
    align-items: center;
    justify-content: space-between;
    padding: 0.8rem 1rem;
    border-bottom: 1px solid var(--field-border);
    text-transform: uppercase;
    letter-spacing: 0.18em;
    font-size: 0.8rem;
    color: var(--muted);
}

.pane-toolbar-text span {
    font-size: 0.95rem;
    font-weight: 600;
    color: var(--text);
    letter-spacing: 0.05em;
}

.toolbar-actions {
    display: flex;
    align-items: center;
}

.sample-button {
    border: 1px solid var(--field-border);
    border-radius: 6px;
    padding: 0.35rem 0.65rem;
    background: var(--surface-alt);
    color: var(--accent);
    font-size: 0.85rem;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    gap: 0.35rem;
    cursor: pointer;
}

.sample-button i {
    font-size: 0.85rem;
}

.pane-content {
    padding: 1.2rem;
}

.pane-columns {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 1.2rem;
}

.editor-pane form {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.input-field {
    display: flex;
    flex-direction: column;
    gap: 0.45rem;
}

.input-field label {
    font-weight: 600;
    font-size: 0.95rem;
}

.control-shell {
    position: relative;
}

.control-shell textarea,
.control-shell input,
.control-shell select {
    width: 100%;
    border-radius: 4px;
    border: 1px solid var(--field-border);
    background: var(--field);
    color: var(--text);
    padding: 0.85rem 0.9rem;
    font-size: 0.95rem;
    font-family: 'Space Grotesk', system-ui, sans-serif;
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.control-shell textarea {
    min-height: 220px;
    resize: vertical;
    font-family: ui-monospace, SFMono-Regular, Consolas, 'Space Grotesk', monospace;
}

.control-shell input:focus,
.control-shell textarea:focus,
.control-shell select:focus {
    border-color: var(--accent);
    box-shadow: 0 0 0 1px var(--accent);
    outline: none;
}

[data-theme="dark"] .control-shell textarea,
[data-theme="dark"] .control-shell input,
[data-theme="dark"] .control-shell select {
    border-color: #3f4b68;
}

.inline-action {
    position: absolute;
    top: 0.35rem;
    right: 0.35rem;
    border: none;
    background: transparent;
    color: var(--accent);
    font-size: 0.9rem;
    cursor: pointer;
}

.inline-action i {
    pointer-events: none;
}

input[type="checkbox"] {
    accent-color: var(--accent);
}

.with-unit {
    padding-right: 2.8rem;
}

.field-unit {
    position: absolute;
    top: 50%;
    right: 0.6rem;
    transform: translateY(-50%);
    font-size: 0.8rem;
    font-weight: 600;
    color: var(--muted);
    pointer-events: none;
}

.primary-run {
    border: none;
    border-radius: 4px;
    padding: 0.85rem 1.4rem;
    background: linear-gradient(120deg, var(--accent), var(--accent-cyan));
    color: #fff;
    font-weight: 600;
    width: fit-content;
    cursor: pointer;
}

.outputs-column {
    display: flex;
    flex-direction: column;
    gap: 1rem;
}

.outputs-column--table-only {
    gap: 0.6rem;
}

.form-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    gap: 1rem;
}

.split-extra-fields {
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
}

.gas-conditions-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
    gap: 0.8rem;
    padding-bottom: 0.6rem;
    border-bottom: 1px dashed var(--field-border);
    margin-bottom: 1rem;
}

.direction-tabs,
.mode-tabs {
    display: flex;
    gap: 0.35rem;
    margin-bottom: 0.4rem;
    flex-wrap: wrap;
}

.direction-tab,
.mode-tab {
    border: 1px solid var(--field-border);
    border-radius: 4px;
    padding: 0.4rem 0.8rem;
    background: var(--surface-alt);
    color: var(--muted);
    font-weight: 600;
    font-size: 0.9rem;
    cursor: pointer;
}

.direction-tab.active,
.mode-tab.active {
    background: var(--accent-soft);
    color: var(--accent-strong);
    border-color: var(--accent);
}

.mode-panel {
    border: 1px solid var(--field-border);
    border-radius: 10px;
    padding: 1rem;
    margin-bottom: 1rem;
    background: var(--surface-alt);
}

.mode-description {
    margin-top: 0;
    margin-bottom: 0.8rem;
    font-size: 0.9rem;
    color: var(--muted);
}

.mode-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 0.8rem;
}

.mode-grid .span-full {
    grid-column: 1 / -1;
}



.mixture-columns {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
    gap: 1rem;
}

.mixture-panel {
    border: 1px solid var(--field-border);
    border-radius: 10px;
    background: var(--surface-alt);
    padding: 1rem;
    display: flex;
    flex-direction: column;
    gap: 0.8rem;
}

.mixture-panel--teal {
    border-color: #0ea5e9;
    box-shadow: 0 0 0 1px rgba(14, 165, 233, 0.25);
}

.mixture-panel--amber {
    border-color: #fbbf24;
    box-shadow: 0 0 0 1px rgba(251, 191, 36, 0.25);
}

.mixture-header {
    display: flex;
    align-items: center;
    gap: 0.5rem;
    font-weight: 700;
    text-transform: uppercase;
    letter-spacing: 0.05em;
    font-size: 0.85rem;
    color: var(--muted);
}

.mixture-header i {
    color: var(--accent);
}

.mixture-grid {
    display: flex;
    flex-direction: column;
    gap: 0.7rem;
}

.mixture-advanced .advanced-grid {
    grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
}

.advanced-group {
    margin-top: 1rem;
    border: 1px solid var(--field-border);
    border-radius: 10px;
    background: var(--surface);
    overflow: hidden;
}

.advanced-group summary {
    cursor: pointer;
    padding: 0.75rem 1rem;
    font-weight: 600;
    background: var(--surface-alt);
    border-bottom: 1px solid var(--field-border);
}

.advanced-group[open] summary {
    border-bottom-color: var(--field-border);
}

.advanced-grid {
    padding: 1rem 1.2rem 1.2rem;
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 0.9rem;
}

/* direction/mode tab styles combined above */

.alert-stack {
    display: flex;
    flex-direction: column;
    gap: 0.5rem;
}

.alert {
    padding: 0.8rem 1rem;
    border-left: 3px solid currentColor;
    font-size: 0.9rem;
}

.alert.info { color: var(--alert-info); background: rgba(138, 77, 255, 0.18); }
.alert.success { color: var(--alert-success); background: rgba(20, 179, 255, 0.18); }
.alert.warning { color: var(--alert-warning); background: rgba(245, 185, 66, 0.18); }
.alert.error { color: var(--alert-error); background: rgba(248, 113, 113, 0.18); }

.result-collapse {
    border: 1px solid var(--field-border);
    border-radius: 8px;
    overflow: hidden;
}

.result-collapse summary {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: 0.8rem 1rem;
    cursor: pointer;
    background: var(--surface-alt);
    font-weight: 600;
    font-size: 0.95rem;
}

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

.summary-action {
    border: none;
    background: transparent;
    color: var(--accent);
    font-size: 1rem;
    cursor: pointer;
}

.summary-action i {
    pointer-events: none;
}

.result-collapse textarea {
    width: 100%;
    border: none;
    background: var(--field);
    color: var(--text);
    padding: 1rem;
    min-height: 260px;
    resize: vertical;
    font-family: ui-monospace, SFMono-Regular, Consolas, 'Space Grotesk', monospace;
}

.result-tree {
    margin: 0;
    padding: 0.6rem 0.8rem;
    background: var(--surface-alt);
    border-top: 1px solid var(--field-border);
    font-size: 0.85rem;
    font-family: ui-monospace, SFMono-Regular, Consolas, 'Space Grotesk', monospace;
    overflow: auto;
}

.result-tree ul {
    list-style: none;
    margin: 0;
    padding-left: 0.9rem;
    border-left: 1px solid var(--field-border);
    margin-left: 0.3rem;
}

.result-tree details {
    margin-bottom: 0.2rem;
}

.result-tree summary {
    cursor: pointer;
    font-weight: 600;
    display: inline-flex;
    align-items: center;
    font-size: 0.85rem;
}

.result-tree summary::before {
    content: '▸';
    display: inline-block;
    margin-right: 0.3rem;
    transition: transform 0.2s ease;
    color: var(--muted);
}

.result-tree details[open] > summary::before {
    transform: rotate(90deg);
}

.tree-key {
    color: var(--accent);
}

.tree-value {
    color: var(--accent-cyan);
}

.tree-meta {
    margin-left: 0.3rem;
    font-size: 0.7rem;
    color: var(--muted);
}

.insight-list {
    margin: 0;
    padding-left: 1rem;
}

.table-wrapper {
    overflow-x: auto;
}

.table-wrapper table {
    width: 100%;
    border-collapse: collapse;
}

.table-wrapper th,
.table-wrapper td {
    border: 1px solid var(--field-border);
    padding: 0.5rem;
    text-align: left;
}

.table-wrapper tr[data-severity] td {
    transition: background 0.15s ease;
}

.table-wrapper tr[data-severity="info"] td {
    background: var(--severity-info-bg);
}

.table-wrapper tr[data-severity="warning"] td {
    background: var(--severity-warning-bg);
}

.table-wrapper tr[data-severity="error"] td {
    background: var(--severity-error-bg);
}

.table-wrapper tr[data-severity] td:first-child {
    border-left-width: 3px;
}

.table-wrapper tr[data-severity="info"] td:first-child {
    border-left-color: var(--alert-info);
}

.table-wrapper tr[data-severity="warning"] td:first-child {
    border-left-color: var(--alert-warning);
}

.table-wrapper tr[data-severity="error"] td:first-child {
    border-left-color: var(--alert-error);
}

.workbench-notes {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
    gap: 1rem;
    border-top: 1px solid var(--field-border);
    padding-top: 1rem;
}

.site-footer {
    border-top: 1px solid var(--field-border);
    padding-top: 0.8rem;
    text-align: center;
    color: var(--muted);
    font-size: 0.9rem;
}

.site-footer a {
    color: var(--accent);
    text-decoration: none;
}

.pwa-install-button {
    position: fixed;
    right: 1.5rem;
    bottom: 1.5rem;
    border: none;
    border-radius: 999px;
    padding: 0.75rem 1.2rem;
    background: linear-gradient(135deg, var(--accent), var(--accent-cyan));
    color: #fff;
    font-weight: 600;
    display: flex;
    gap: 0.5rem;
    align-items: center;
    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.25);
    cursor: pointer;
    z-index: 20;
}

.pwa-install-button i {
    font-size: 1rem;
}

.pwa-install-button[hidden] {
    display: none;
}

[data-error-target] {
    transition: border-color 0.2s ease, box-shadow 0.2s ease;
}

.column-error,
[data-error-target].column-error {
    border-color: var(--alert-error);
    box-shadow: 0 0 0 2px rgba(248, 113, 113, 0.35);
}

.split-layout .pane-content {
    padding: 1rem 0.5rem 1rem;
}

.split-layout .pane-columns {
    display: block;
}

.split-grid {
    display: flex;
    gap: 0.75rem;
    align-items: stretch;
}

.split-layout .tool-form {
    display: flex;
    flex-direction: column;
    flex: 2;
    gap: 0.75rem;
}

.split-version-bar {
    margin-bottom: 0.2rem;
}

.split-columns {
    display: flex;
    gap: 0.75rem;
    align-items: stretch;
}

.split-layout .split-column,
.split-layout .split-output {
    background: var(--surface);
    border-radius: 16px;
    padding: 0.9rem;
    border: 1px solid transparent;
    min-width: 240px;
    display: flex;
    flex-direction: column;
    flex: 1 1 0;
    position: relative;
}

.split-layout .split-column .control-shell textarea,
.split-layout .split-column .control-shell textarea:focus {
    background: var(--surface-alt);
    border: none;
    min-height: 420px;
    font-family: 'Space Grotesk', monospace;
    font-size: 0.9rem;
    resize: none;
}

.split-layout .split-output textarea {
    min-height: 420px;
}

.split-column-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    font-weight: 600;
    font-size: 0.95rem;
    margin-bottom: 0.5rem;
}

.column-fullscreen-toggle {
    border: none;
    background: transparent;
    color: var(--muted);
    cursor: pointer;
    font-size: 0.95rem;
}

.column-fullscreen-toggle:focus-visible {
    outline: 2px solid var(--accent);
    border-radius: 4px;
}

.split-layout .split-run {
    align-self: flex-end;
}

.split-resizer {
    width: 6px;
    cursor: col-resize;
    border-radius: 3px;
    background: var(--field-border);
    opacity: 0.3;
    min-height: 200px;
    align-self: stretch;
}

.split-resizer:hover {
    opacity: 0.6;
}

.split-layout .split-column.fullscreen,
.split-layout .split-output.fullscreen {
    position: fixed;
    inset: 2rem;
    z-index: 60;
    background: var(--surface);
    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.45);
}

body.split-fullscreen-active {
    overflow: hidden;
}

.xslt-column-body {
    margin-top: 0.6rem;
}

@media (max-width: 640px) {
    .top-bar {
        flex-direction: column;
        align-items: flex-start;
        gap: 0.5rem;
        height: auto;
    }
}
.tree-meta {
    margin-left: 0.4rem;
    font-size: 0.78rem;
    color: var(--muted);
}
.toggle-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 1rem;
    padding: 0.5rem 0;
}

.toggle-text {
    font-size: 0.92rem;
    font-weight: 600;
}

.toggle-switch {
    position: relative;
    width: 56px;
    height: 28px;
}

.toggle-switch input {
    opacity: 0;
    width: 0;
    height: 0;
}

.toggle-slider {
    position: absolute;
    inset: 0;
    border-radius: 999px;
    background: var(--field-border);
    transition: background 0.2s;
}

.toggle-slider::before {
    content: "";
    position: absolute;
    width: 22px;
    height: 22px;
    left: 3px;
    top: 3px;
    border-radius: 50%;
    background: var(--surface);
    transition: transform 0.2s;
}

.toggle-switch input:checked + .toggle-slider {
    background: var(--accent);
}

.toggle-switch input:checked + .toggle-slider::before {
    transform: translateX(28px);
}

.toggle-field {
    grid-column: 1 / -1;
}
.not-found-shell {
    min-height: 100vh;
}

.not-found {
    display: flex;
    align-items: center;
    justify-content: center;
    padding: 3rem 1rem;
}

.not-found-card {
    max-width: 520px;
    text-align: center;
    padding: 2rem;
    border-radius: 16px;
    border: 1px solid var(--field-border);
    background: var(--surface);
    box-shadow: 0 10px 36px rgba(0, 0, 0, 0.25);
}

.not-found-card h1 {
    font-size: 2rem;
    margin-bottom: 1rem;
}

.not-found-card p {
    color: var(--muted);
    margin-bottom: 0.8rem;
}

.not-found-card a {
    color: var(--accent);
    text-decoration: none;
    font-weight: 600;
}

.not-found-actions {
    margin: 1rem 0;
}

.not-found-actions .ghost-link {
    display: inline-flex;
    align-items: center;
    gap: 0.5rem;
    border: 1px dashed var(--accent);
    padding: 0.5rem 1rem;
    border-radius: 999px;
}