/*
 * Multifractal Explorer — Atlas theme.
 * Parchment + ink + sienna, no card containers. Controls flow as
 * typographic sections separated by hairlines, matching the thought-cloud
 * index page rather than the older boxed-card tools.
 */

/* ===== CSS Custom Properties ===== */
:root {
    /* Atlas palette */
    --bg-warm: #f4efe5;
    --text-primary: #2b1f15;
    --text-muted: #6b5840;
    --text-faint: #a8967a;
    --text-active: #b8431f;
    --accent: #b8431f;
    --rule: rgba(43, 31, 21, 0.10);
    --rule-strong: rgba(43, 31, 21, 0.20);
    --tint-soft: rgba(43, 31, 21, 0.04);
    --tint-warm: rgba(184, 67, 31, 0.08);

    --header-height: 64px;
    --sidebar-width: 320px;
    --content-gap: 2.5rem;
    --transition-fast: 0.15s ease;
    --transition-medium: 0.3s ease;

    --font-sans: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    --font-serif: 'EB Garamond', Georgia, serif;
    --font-mono: 'IBM Plex Mono', ui-monospace, Menlo, monospace;

    --cursor-plus: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24'><g fill='%23b8431f'><polygon points='12,2 10,9.8 14,9.8'/><polygon points='22,12 14.2,10 14.2,14'/><polygon points='12,22 10,14.2 14,14.2'/><polygon points='2,12 9.8,10 9.8,14'/></g><circle cx='12' cy='12' r='1' fill='%232b1f15'/></svg>") 12 12, crosshair;
    --cursor-plus-click: url("data:image/svg+xml,<svg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24'><g fill='%23b8431f'><polygon points='12,2 10,9.8 14,9.8'/><polygon points='22,12 14.2,10 14.2,14'/><polygon points='12,22 10,14.2 14,14.2'/><polygon points='2,12 9.8,10 9.8,14'/></g><rect x='10' y='10' width='4' height='4' fill='%232b1f15'/></svg>") 12 12, pointer;
}

/* ===== Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html, body { height: 100%; }
html {
    font-size: 16px;
    -webkit-font-smoothing: antialiased;
    -moz-osx-font-smoothing: grayscale;
}

body {
    font-family: var(--font-serif);
    background-color: var(--bg-warm);
    color: var(--text-primary);
    line-height: 1.5;
    cursor: var(--cursor-plus);
}

a, button, [role="button"],
input[type="range"], input[type="checkbox"], input[type="number"],
input[type="number"]::-webkit-inner-spin-button,
input[type="number"]::-webkit-outer-spin-button,
label, select, summary {
    cursor: var(--cursor-plus-click);
}

a:active, button:active, [role="button"]:active {
    cursor: var(--cursor-plus-click);
}

/* ===== Header (matches rest of site) ===== */
.site-header {
    position: fixed;
    top: 0; left: 0; right: 0;
    z-index: 1000;
    display: flex;
    align-items: center;
    height: var(--header-height);
    padding: 0 1.5rem;
    background: linear-gradient(to bottom, var(--bg-warm) 0%, var(--bg-warm) 80%, transparent 100%);
    font-family: var(--font-sans);
    font-size: 0.875rem;
}

.site-nav {
    display: flex;
    align-items: center;
    gap: 1.5rem;
}

.nav-item { position: relative; display: flex; align-items: center; }

.nav-link {
    color: var(--text-muted);
    text-decoration: none;
    letter-spacing: 0.02em;
    transition: color var(--transition-fast);
    padding: 0.5rem 0;
    display: block;
}

.nav-link:hover { color: var(--text-primary); text-decoration: none; }
.nav-link em { font-style: italic; }
.nav-link.active { color: var(--text-active); }

.nav-item.static-breadcrumb { display: flex; align-items: center; }
.breadcrumb-divider {
    margin: 0 0.5rem;
    color: var(--text-faint);
    flex-shrink: 0;
}
.breadcrumb-current {
    color: var(--text-faint);
    font-style: italic;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    max-width: 30vw;
    display: inline-block;
    padding: 0.5rem 0;
}

.hamburger {
    display: none;
    flex-direction: column;
    justify-content: center;
    gap: 5px;
    width: 24px; height: 24px;
    background: none; border: none; padding: 0;
    margin-left: auto;
}
.hamburger span {
    display: block;
    width: 100%; height: 2px;
    background: var(--text-primary);
    transition: transform var(--transition-fast), opacity var(--transition-fast);
}

.mobile-menu {
    position: fixed;
    inset: 0;
    background: var(--bg-warm);
    z-index: 999;
    opacity: 0;
    visibility: hidden;
    transition: opacity var(--transition-medium), visibility 0s var(--transition-medium);
}
.mobile-menu.open {
    opacity: 1;
    visibility: visible;
    transition: opacity var(--transition-medium), visibility 0s 0s;
}
.mobile-menu-content { padding: calc(var(--header-height) + 2rem) 1.5rem 2rem; }
.mobile-menu .mobile-nav-item { margin-bottom: 1.5rem; }
.mobile-menu .mobile-nav-link {
    display: block;
    font-size: 1.25rem;
    color: var(--text-primary);
    text-decoration: none;
    margin-bottom: 0.5rem;
}
.mobile-menu .mobile-nav-link em { font-style: italic; }
.mobile-menu .mobile-nav-link.active { color: var(--text-active); }

/* ===== Main Content ===== */
.content {
    min-height: calc(100vh - var(--header-height));
    padding: calc(var(--header-height) + 1rem) 1.5rem 1.5rem;
}

.main-layout {
    display: flex;
    gap: var(--content-gap);
    min-height: calc(100vh - var(--header-height) - 2.5rem);
    align-items: flex-start;
}

/* ===== Visualization — fills available height, sits on parchment ===== */
.visualization-section {
    flex: 1;
    min-width: 0;
    display: flex;
    align-items: flex-start;
    justify-content: center;
    position: sticky;
    top: calc(var(--header-height) + 1rem);
    align-self: flex-start;
}

.plot-container {
    position: relative;
    width: 100%;
    aspect-ratio: 1 / 1;
}

.plot-area {
    width: 100%;
    height: 100%;
    display: block;
}

/* ===== Sidebar — no card; controls as typographic sections ===== */
.sidebar {
    flex: 0 0 var(--sidebar-width);
    display: flex;
    flex-direction: column;
    font-family: var(--font-sans);
}

.control-section {
    padding: 0.55rem 0;
    border-bottom: 1px solid var(--rule);
}
.control-section:first-child { padding-top: 0; }
.control-section.no-rule { border-bottom: none; }

.section-label {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    letter-spacing: 0.16em;
    text-transform: uppercase;
    color: var(--text-faint);
    margin-bottom: 0.35rem;
    display: block;
}
.section-label + .section-label,
.section-label.inline-top { margin-top: 0.6rem; }

/* Dimension switch — text buttons with sienna underline */
.dimension-buttons {
    display: flex;
    gap: 1.75rem;
}
.dimension-btn {
    background: none;
    border: none;
    padding: 0.35rem 0;
    color: var(--text-muted);
    font-family: var(--font-sans);
    font-size: 1rem;
    font-weight: 400;
    letter-spacing: 0.04em;
    border-bottom: 1px solid transparent;
    transition: color var(--transition-fast), border-color var(--transition-fast);
}
.dimension-btn:hover { color: var(--text-primary); }
.dimension-btn.active {
    color: var(--accent);
    border-bottom-color: var(--accent);
}

/* Grid size — label on the left, power-of-2 stepper on the right */
.size-row {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 0.6rem;
    align-items: center;
    margin-bottom: 0.35rem;
}
.size-row:last-child { margin-bottom: 0; }
.size-row label {
    font-family: var(--font-sans);
    font-size: 0.82rem;
    color: var(--text-primary);
}

/* 2^[exp] = value — the input changes the exponent, the running value
   is computed and shown to the right for context. */
.pow2-input {
    display: inline-flex;
    align-items: baseline;
    gap: 0.35rem;
    font-family: var(--font-mono);
    font-size: 0.78rem;
}
.pow2-input .pow2-base { color: var(--text-muted); }
.pow2-input .exp-input {
    width: 2.6rem;
    padding: 0.22rem 0.35rem;
    border: 1px solid var(--rule-strong);
    background: transparent;
    font-family: var(--font-mono);
    font-size: 0.78rem;
    color: var(--text-primary);
    text-align: right;
    border-radius: 0;
    transition: border-color var(--transition-fast);
    font-variant-numeric: tabular-nums;
}
.pow2-input .exp-input:focus {
    outline: none;
    border-color: var(--accent);
}
/* Hide the browser's native number-input spinner arrows. The input is
   semantically a power-of-two exponent (the bare number is meaningless
   in context) — the spinner glyphs read as visual noise next to the
   "2^" label. Keyboard arrow keys still step the value. */
.pow2-input .exp-input::-webkit-outer-spin-button,
.pow2-input .exp-input::-webkit-inner-spin-button {
    -webkit-appearance: none;
    margin: 0;
}
.pow2-input .exp-input {
    -moz-appearance: textfield;
    appearance: textfield;
}
.pow2-input .pow2-value {
    color: var(--text-faint);
    font-variant-numeric: tabular-nums;
}

/* Slider rows — label + value above a thin track */
.slider-row { margin-bottom: 0.35rem; }
.slider-row:last-child { margin-bottom: 0; }
.row-head {
    display: flex;
    justify-content: space-between;
    align-items: baseline;
    margin-bottom: 0.18rem;
}
.slider-row label {
    font-family: var(--font-sans);
    font-size: 0.82rem;
    color: var(--text-primary);
    letter-spacing: 0.01em;
}
.slider-row .value {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    color: var(--text-muted);
    font-variant-numeric: tabular-nums;
}
.slider-row input[type="range"] {
    -webkit-appearance: none;
    appearance: none;
    width: 100%;
    height: 2px;
    background: var(--rule-strong);
    outline: none;
    border-radius: 1px;
    margin: 4px 0;
}
.slider-row input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 12px; height: 12px;
    border-radius: 50%;
    background: var(--text-primary);
    border: none;
    box-shadow: 0 0 0 2px var(--bg-warm);
    transition: background-color var(--transition-fast), box-shadow var(--transition-fast);
}
.slider-row input[type="range"]::-webkit-slider-thumb:hover {
    background: var(--accent);
    box-shadow: 0 0 0 2px var(--bg-warm), 0 0 0 5px var(--tint-warm);
}
.slider-row input[type="range"]::-moz-range-thumb {
    width: 12px; height: 12px;
    border-radius: 50%;
    background: var(--text-primary);
    border: none;
    box-shadow: 0 0 0 2px var(--bg-warm);
}
.slider-row input[type="range"]::-moz-range-thumb:hover {
    background: var(--accent);
}

/* Inline toggle group — for view / colormap */
.toggle-grid {
    display: grid;
    gap: 0;
    border: 1px solid var(--rule-strong);
    background: transparent;
}
.toggle-grid.cols-2 { grid-template-columns: 1fr 1fr; }
.toggle-grid.cols-3 { grid-template-columns: 1fr 1fr 1fr; }
.toggle-grid.cols-4 { grid-template-columns: 1fr 1fr 1fr 1fr; }

.toggle-btn {
    padding: 0.45rem 0.5rem;
    background: transparent;
    border: none;
    border-right: 1px solid var(--rule-strong);
    color: var(--text-muted);
    font-family: var(--font-sans);
    font-size: 0.78rem;
    letter-spacing: 0.02em;
    transition: all var(--transition-fast);
    text-align: center;
}
.toggle-grid > .toggle-btn:last-child { border-right: none; }
.toggle-btn:hover {
    color: var(--text-primary);
    background: var(--tint-soft);
}
.toggle-btn.active {
    color: var(--accent);
    background: var(--tint-warm);
    font-weight: 500;
}

/* Kernel selector (1D) — same toggle look, with an SVG glyph */
.kernel-btn {
    padding: 0.45rem 0.3rem 0.35rem;
    background: transparent;
    border: none;
    border-right: 1px solid var(--rule-strong);
    color: var(--text-muted);
    font-family: var(--font-sans);
    font-size: 0.72rem;
    letter-spacing: 0.02em;
    transition: all var(--transition-fast);
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.2rem;
}
.toggle-grid > .kernel-btn:last-child { border-right: none; }
.kernel-btn svg {
    width: 100%;
    max-width: 40px;
    height: 18px;
    overflow: visible;
}
.kernel-btn svg path {
    fill: none;
    stroke: var(--text-muted);
    stroke-width: 1.4;
    stroke-linecap: round;
    stroke-linejoin: round;
    transition: stroke var(--transition-fast);
}
.kernel-btn:hover {
    color: var(--text-primary);
    background: var(--tint-soft);
}
.kernel-btn:hover svg path { stroke: var(--text-primary); }
.kernel-btn.active {
    color: var(--accent);
    background: var(--tint-warm);
    font-weight: 500;
}
.kernel-btn.active svg path { stroke: var(--accent); }

/* Per-axis kernel + periodic — one row per axis (X/Y/T) */
.axis-row {
    display: grid;
    grid-template-columns: 1.1rem 1fr auto;
    align-items: center;
    gap: 0.55rem;
    margin-bottom: 0.45rem;
}
.axis-row:last-child { margin-bottom: 0; }
.axis-row .axis-label {
    font-family: var(--font-mono);
    font-size: 0.72rem;
    letter-spacing: 0.1em;
    color: var(--text-muted);
}
.axis-row .axis-periodic {
    display: flex;
    align-items: center;
    gap: 0.3rem;
    font-family: var(--font-sans);
    font-size: 0.72rem;
    color: var(--text-muted);
    white-space: nowrap;
}
.axis-row .axis-periodic input[type="checkbox"] {
    width: 13px;
    height: 13px;
    accent-color: var(--accent);
}
.axis-row .toggle-grid { width: 100%; }
.axis-row .kernel-btn {
    padding: 0.32rem 0.2rem 0.28rem;
    font-size: 0.65rem;
}
.axis-row .kernel-btn svg { max-width: 34px; height: 14px; }

/* Disabled (incompatible) kernel option — grayed but still readable */
.toggle-btn.disabled, .kernel-btn.disabled,
.toggle-btn[disabled], .kernel-btn[disabled] {
    opacity: 0.32;
    pointer-events: none;
}

/* 3D scrubber row, sits below the plot, same max-width */
.scrubber-row {
    display: flex;
    align-items: center;
    gap: 0.6rem;
    margin-top: 0.6rem;
    width: 100%;
    font-family: var(--font-sans);
    font-size: 0.78rem;
}
.scrubber-row .play-btn {
    width: 26px;
    height: 26px;
    border: 1px solid var(--rule-strong);
    background: transparent;
    color: var(--text-primary);
    display: flex;
    align-items: center;
    justify-content: center;
    border-radius: 0;
    transition: all var(--transition-fast);
    font-size: 0.7rem;
    flex-shrink: 0;
    padding: 0;
}
.scrubber-row .play-btn:hover {
    color: var(--accent);
    border-color: var(--accent);
}
.scrubber-row input[type="range"] {
    flex: 1;
    -webkit-appearance: none;
    appearance: none;
    height: 2px;
    background: var(--rule-strong);
    outline: none;
    border-radius: 1px;
    margin: 4px 0;
}
.scrubber-row input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    appearance: none;
    width: 13px; height: 13px;
    border-radius: 50%;
    background: var(--accent);
    border: none;
    box-shadow: 0 0 0 2px var(--bg-warm);
}
.scrubber-row input[type="range"]::-moz-range-thumb {
    width: 13px; height: 13px;
    border-radius: 50%;
    background: var(--accent);
    border: none;
}
.scrubber-row .time-display {
    font-family: var(--font-mono);
    font-size: 0.7rem;
    color: var(--text-muted);
    font-variant-numeric: tabular-nums;
    min-width: 5rem;
    text-align: right;
}

/* Listen button — small chip beneath the action row, 1D only */
.listen-row {
    display: flex;
    margin-top: 0.55rem;
}
.listen-btn {
    flex: 1;
    padding: 0.55rem 0.75rem;
    background: transparent;
    color: var(--text-primary);
    border: 1px solid var(--accent);
    font-family: var(--font-mono);
    font-size: 0.7rem;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    border-radius: 0;
    transition: all var(--transition-fast);
}
.listen-btn:hover {
    background: var(--accent);
    color: var(--bg-warm);
}
.listen-btn.playing {
    background: var(--accent);
    color: var(--bg-warm);
}

/* Viz section now stacks (plot above scrubber).
   Default flow: square plot (the heatmap / 1D line plot want 1:1).
   Relief mode: drop the square constraint and let the wireframe fill the
   entire available width × height — multifractal terrain reads much better
   when it has horizontal room to breathe. */
.viz-stack {
    display: flex;
    flex-direction: column;
    align-items: center;
    width: 100%;
    max-width: calc(100vh - var(--header-height) - 2.5rem);
}
/* 3D adds a scrubber row beneath the plot. The plot's aspect-ratio:1/1
   in Flat mode would otherwise push the scrubber off the viewport — so
   reserve ~3rem of vertical budget for the scrubber inside the
   viewport-height calculation. */
.viz-stack.has-scrubber {
    max-width: calc(100vh - var(--header-height) - 5.5rem);
}
.viz-stack.relief-mode {
    max-width: 100%;
    height: calc(100vh - var(--header-height) - 2.5rem);
}
.viz-stack.relief-mode .plot-container {
    aspect-ratio: auto;
    flex: 1;
    min-height: 0;
    width: 100%;
}

/* Checkbox rows */
.checkbox-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: 0.55rem;
}
.checkbox-row:last-child { margin-bottom: 0; }
.checkbox-row label {
    font-family: var(--font-sans);
    font-size: 0.82rem;
    color: var(--text-primary);
}
.checkbox-row input[type="checkbox"] {
    width: 14px; height: 14px;
    accent-color: var(--accent);
}
.checkbox-row input[type="checkbox"]:disabled {
    opacity: 0.4;
}
.checkbox-row input[type="checkbox"]:disabled + label,
.checkbox-row.disabled label {
    opacity: 0.5;
}

/* Buttons */
.button-row {
    display: flex;
    gap: 0.5rem;
    flex-wrap: wrap;
}
.primary-btn, .secondary-btn {
    flex: 1;
    min-width: 0;
    padding: 0.6rem 0.6rem;
    font-family: var(--font-mono);
    font-size: 0.7rem;
    letter-spacing: 0.14em;
    text-transform: uppercase;
    transition: all var(--transition-fast);
    border-radius: 0;
    white-space: nowrap;
}
.primary-btn {
    background: var(--text-primary);
    color: var(--bg-warm);
    border: 1px solid var(--text-primary);
}
.primary-btn:hover {
    background: var(--accent);
    border-color: var(--accent);
    color: var(--bg-warm);
}
.secondary-btn {
    background: transparent;
    color: var(--text-primary);
    border: 1px solid var(--rule-strong);
}
.secondary-btn:hover {
    color: var(--accent);
    border-color: var(--accent);
}

/* Dirty pulse for Simulate — sienna instead of grey */
.primary-btn.dirty {
    animation: simulate-dirty-pulse 1.4s ease-in-out infinite;
}
@keyframes simulate-dirty-pulse {
    0%, 100% { box-shadow: 0 0 0 0 rgba(184, 67, 31, 0.0); }
    50%      { box-shadow: 0 0 0 4px rgba(184, 67, 31, 0.22); }
}

.plot-area.stale {
    opacity: 0.35;
    transition: opacity 0.18s ease;
    pointer-events: none;
}

/* ===== About — inline expanding, no card ===== */
.about-section {
    padding: 1.1rem 0 0;
}
.about-toggle {
    width: 100%;
    display: flex;
    align-items: center;
    justify-content: space-between;
    background: none;
    border: none;
    padding: 0.3rem 0;
    font-family: var(--font-mono);
    font-size: 0.65rem;
    letter-spacing: 0.16em;
    text-transform: uppercase;
    color: var(--text-faint);
    text-align: left;
    transition: color var(--transition-fast);
}
.about-toggle:hover { color: var(--text-primary); }
.about-arrow {
    font-size: 0.65rem;
    transition: transform var(--transition-fast);
}
.about-content {
    max-height: 0;
    overflow: hidden;
    transition: max-height var(--transition-medium);
}
.about-content.open {
    max-height: 900px;
    padding-top: 0.75rem;
}
.about-content p {
    font-family: var(--font-serif);
    font-size: 0.98rem;
    line-height: 1.65;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
}
.about-content p:last-child { margin-bottom: 0; }
.about-content ul {
    margin: 0.5rem 0 0.85rem;
    padding-left: 1.25rem;
    font-family: var(--font-serif);
    font-size: 0.98rem;
}
.about-content li {
    margin-bottom: 0.35rem;
    line-height: 1.6;
}
.about-content a {
    color: var(--text-primary);
    text-decoration: underline;
    text-decoration-color: var(--accent);
    text-decoration-thickness: 1px;
    text-underline-offset: 2px;
    transition: color var(--transition-fast);
}
.about-content a:hover { color: var(--accent); }
.about-content strong { font-weight: 600; }

/* Download options popup — native <dialog>, parchment-themed.
   Some browsers don't auto-centre <dialog> reliably; explicit fixed
   positioning + translate handles it portably. */
.download-dialog {
    position: fixed;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    margin: 0;
    padding: 1.25rem 1.5rem;
    border: 1px solid var(--rule-strong);
    background: var(--bg-warm);
    color: var(--text-primary);
    border-radius: 0;
    font-family: var(--font-sans);
    min-width: 320px;
    max-width: 90vw;
    box-shadow: 0 8px 32px rgba(43, 31, 21, 0.25);
}
.download-dialog::backdrop {
    background: rgba(43, 31, 21, 0.35);
}
.download-dialog .dl-title {
    font-family: var(--font-mono);
    font-size: 0.65rem;
    letter-spacing: 0.16em;
    text-transform: uppercase;
    color: var(--text-faint);
    margin-bottom: 0.9rem;
}
.download-dialog .dl-row {
    display: grid;
    grid-template-columns: 1fr auto;
    gap: 0.8rem;
    align-items: center;
    margin-bottom: 0.7rem;
}
.download-dialog .dl-row label {
    font-size: 0.85rem;
    color: var(--text-primary);
}
.download-dialog .dl-fmt-group {
    width: 8rem;
}
.download-dialog #dl-width {
    width: 4.5rem;
    text-align: right;
}
.download-dialog .dl-note {
    font-size: 0.75rem;
    color: var(--text-muted);
    font-style: italic;
    margin: 0.2rem 0 0.6rem;
    line-height: 1.4;
}
.download-dialog .dl-actions {
    display: flex;
    gap: 0.5rem;
    justify-content: flex-end;
    margin-top: 1rem;
}
.download-dialog .dl-actions button {
    flex: 0 0 auto;
    min-width: 6rem;
}

/* Audio-playback cursor — thin sienna line that scrolls across the 1D
   line plot from left to right as the sonifier plays. */
#audio-cursor {
    position: absolute;
    top: 0;
    bottom: 0;
    width: 1.5px;
    background: var(--accent);
    pointer-events: none;
    z-index: 5;
    opacity: 0.75;
    box-shadow: 0 0 6px rgba(184, 67, 31, 0.35);
    display: none;
}

/* ===== Loading overlay — parchment-tinted, sienna spinner ===== */
.loading-overlay {
    position: absolute;
    inset: 0;
    background: rgba(244, 239, 229, 0.88);
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    z-index: 10;
}
.loading-spinner {
    width: 28px; height: 28px;
    border: 2px solid var(--rule);
    border-top-color: var(--accent);
    border-radius: 50%;
    animation: spin 1s linear infinite;
    margin-bottom: 0.85rem;
}
@keyframes spin { to { transform: rotate(360deg); } }
.loading-text {
    color: var(--text-muted);
    font-family: var(--font-mono);
    font-size: 0.7rem;
    letter-spacing: 0.16em;
    text-transform: uppercase;
}
.loading-progress {
    width: 140px; height: 2px;
    background: var(--rule);
    margin-top: 0.6rem;
    overflow: hidden;
}
.loading-progress-bar {
    height: 100%;
    background: var(--accent);
    width: 0%;
    transition: width 0.3s ease;
}

/* ===== Error ===== */
.error-message {
    background: var(--tint-warm);
    border-left: 2px solid var(--accent);
    padding: 0.75rem 1rem;
    margin-bottom: 0.75rem;
    color: var(--text-primary);
    font-family: var(--font-sans);
    font-size: 0.85rem;
    display: flex;
    align-items: center;
    gap: 0.6rem;
}
.error-message .error-icon { font-size: 1rem; flex-shrink: 0; }
.error-message .error-text { flex: 1; }

/* First-load nudge that the sidebar continues below the fold. Sits in
   the bottom-right corner (under the sidebar), bounces gently, and is
   removed on the first scroll gesture. Hidden by default — `.visible`
   is toggled in JS only when there's real overflow. */
/* Horizontal position + width are set by JS to match the sidebar's
   bounding rect (so the cue lives over the scrolling column, not the
   centered visualization). The background is a soft vertical fade so
   the bottom of the page looks like it's dissolving into parchment —
   a visual metaphor for "more content continues off-screen". */
#scroll-cue {
    position: fixed;
    bottom: 0;
    /* `left` and `width` are written by JS; defaults keep it off-screen
       until the first measurement lands. */
    left: 0;
    width: 0;
    padding: 2.25rem 0 0.9rem;
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.1rem;
    pointer-events: none;
    z-index: 20;
    background: linear-gradient(
        to bottom,
        rgba(244, 239, 229, 0) 0%,
        rgba(244, 239, 229, 0.55) 40%,
        rgba(244, 239, 229, 0.92) 75%,
        var(--bg-warm) 100%
    );
    font-family: var(--font-mono);
    font-size: 0.62rem;
    letter-spacing: 0.16em;
    text-transform: uppercase;
    color: var(--sienna);
    opacity: 0;
    transition: opacity 0.45s ease-out;
}
#scroll-cue.visible {
    opacity: 1;
}
.scroll-cue-arrow {
    font-size: 1.35rem;
    line-height: 1;
    animation: scroll-cue-bounce 1.6s ease-in-out infinite;
}
@keyframes scroll-cue-bounce {
    0%, 100% { transform: translateY(0); }
    50%      { transform: translateY(6px); }
}
@media (max-width: 768px) {
    #scroll-cue { display: none; }
}

/* Mobile-only notice. The explorer wasn't designed for touch — calling
   it out is more honest than letting the layout silently degrade. */
.mobile-notice {
    display: none;
}
@media (max-width: 768px) {
    .mobile-notice {
        display: block;
        margin: calc(var(--header-height) + 0.75rem) 1rem 0;
        padding: 0.75rem 1rem;
        background: var(--tint-warm);
        border-left: 2px solid var(--accent);
        font-family: var(--font-sans);
        font-size: 0.85rem;
        line-height: 1.5;
        color: var(--text-primary);
    }
    /* The mobile notice already pushed everything down — drop the content's
       padding-top so we don't double up. */
    .content { padding-top: 1rem !important; }
}

/* ===== Responsive ===== */
@media (max-width: 1100px) {
    :root { --sidebar-width: 280px; --content-gap: 1.75rem; }
}

@media (max-width: 900px) {
    :root { --sidebar-width: 260px; --content-gap: 1.5rem; }
}

@media (max-width: 768px) {
    :root { --header-height: 56px; --sidebar-width: 100%; }
    .site-header { padding: 0 1rem; }
    .site-nav { display: none; }
    .hamburger { display: flex; }
    .site-header.menu-open .hamburger span:nth-child(1) {
        transform: rotate(45deg) translate(5px, 5px);
    }
    .site-header.menu-open .hamburger span:nth-child(2) { opacity: 0; }
    .site-header.menu-open .hamburger span:nth-child(3) {
        transform: rotate(-45deg) translate(5px, -5px);
    }
    .content {
        padding: calc(var(--header-height) + 1rem) 1rem 2rem;
        position: relative;
        min-height: 100vh;
    }
    .main-layout {
        flex-direction: column;
        gap: 1.5rem;
        align-items: stretch;
    }
    .visualization-section {
        position: relative;
        top: auto;
        width: 100%;
        justify-content: center;
    }
    .plot-container {
        max-width: 100%;
        width: 100%;
    }
    .sidebar { flex: none; width: 100%; }
}

@media (max-width: 480px) {
    .content { padding: calc(var(--header-height) + 0.75rem) 0.75rem 1.5rem; }
    .toggle-grid.cols-4 { grid-template-columns: 1fr 1fr; }
    .toggle-grid.cols-4 > .toggle-btn:nth-child(2) { border-right: none; }
    .toggle-grid.cols-4 > .toggle-btn:nth-child(3),
    .toggle-grid.cols-4 > .toggle-btn:nth-child(4) {
        border-top: 1px solid var(--rule-strong);
    }
}

@media print {
    .site-header { display: none; }
    .content { padding: 1rem; }
}