/* ============================================================
   MRI Simulator, design system

   One stylesheet for the shell and every tab. Tabs add their own
   rules with MRI.ui.addStyle(), scoped under #tab-<id>, and should
   build their layouts from the classes below rather than inventing
   new ones, so the whole instrument looks like one piece.

   TOKENS (CSS custom properties on :root; light and dark sets)
     Surfaces   --bg --card --card-2 (inset/sub-surface) --hover
     Text       --fg --muted (both >= 4.5:1 on every surface) --faint (decoration only, 3:1)
     Lines      --border --border-strong --border-subtle --grid --axis
     Accent     --accent (text, focus, indicators) --accent-strong (button fill)
                --accent-soft (tinted background) --accent-border --on-accent
                --accent-ink (small accent text on a tint: >= 4.5:1 there)
     Status     --good --warn --bad (+ -soft and -border variants);
                --good-ink (small green text on a tint, as --accent-ink)
     Scopes     --scope-bg --scope-fg --scope-muted --scope-grid --scope-axis
                --scope-border. Images and oscilloscope-like plots sit on
                these near-black values in BOTH themes.
     Series     --c1 .. --c8 for plots on cards (theme aware),
                --sc1 .. --sc8 for plots on scopes. Use in this order.
     Sequence   --seq-rf --seq-gx --seq-gy --seq-gz --seq-adc: the channel
                colours shared by the timing diagram, the scanner schematic
                and anything else that shows RF, gradients or the ADC.
     Type       --font-sans --font-mono --font-math
     Shape      --radius (10px cards) --radius-sm (6px controls) --ctl-h (32px)
                --shadow-1 --shadow-2 --gutter (16px) --maxw (1280px)
     Shell      --console-h: height of the sticky scan bar + tab bar, kept
                current by app.js (0 when the console scrolls away). html has
                scroll-padding-top from it, so focus and scrollIntoView stop
                below the console (content only: focusing a console control
                never scrolls the page); use it for any sticky offset in a tab.
     Canvas code reads these with MRI.util.cssVar('--c1') and redraws
     on the 'theme:changed' bus event.

   LAYOUT
     .panel                  card: background, border, 10px radius, padding
       .panel-head           title row: .panel-title + .panel-sub + actions on the right
       .panel-flush          panel without inner padding (for full-bleed content)
     .grid                   auto-fit columns, each at least --min (default 260px);
                             set style="--min: 200px" to change
     .grid-2 .grid-3         fixed 2 or 3 columns that collapse on narrow screens
     .split                  main column + 340px side column, stacks below 900px
     .split-even             two equal columns, stacks below 760px
     .row                    flex row with wrapping and a 8px/12px gap
     .stack                  vertical stack with 12px gaps (.stack-sm 6px, .stack-lg 20px)
     .spacer                 flex: 1 inside a .row (pushes the rest to the right)
     .toolbar                compact row of controls (buttons, selects) with wrapping

   TEACHING
     .concept                the concept card (built by MRI.ui.w.concept): a
                             <details> with .concept-head, .concept-body,
                             .concept-formula, .concept-try
     .callout                tinted note; .callout-warn .callout-bad .callout-good
     .note                   small muted paragraph
     .simplification         "honest simplification" note (italic, dotted border)

   CONTROLS (built by MRI.ui.w where possible)
     .controls               grid of control rows (sliders, selects), auto-fit 200px
     .ctl                    one control: .ctl-label + .ctl-value, then the input;
                             .ctl-inline puts label and control on one line
     .btn                    button; .btn-primary .btn-ghost .btn-danger;
                             sizes .btn-sm .btn-xs; .btn-block full width.
                             A bare <button> without a class gets the .btn look.
     .btn-group              joined buttons
     .seg                    segmented control (radio group); .seg-sm
     .toggle                 switch: <label class="toggle"><input type=checkbox>
                             <span class="toggle-track"></span><span class="toggle-label">
     .select, select         drop-down; .select-sm
     .input                  text/number input (also input[type=number] etc.)
     .check                  plain checkbox with label
     input[type=range]       styled globally; set --fill: NN% for the filled part

   DATA
     .stat-table             label/value table (MRI.ui.w.statTable); .unit spans
     .stats + .stat          tiles: .stat-label .stat-value .stat-unit
     .badge                  pill; .badge-accent .badge-good .badge-warn .badge-bad .badge-muted
     .legend + .legend-item  legend row; .swatch (square), .swatch-line, .swatch-dash
     .kbd, kbd, code, .mono, .num (tabular numbers)

   DISPLAYS
     .well                   near-black frame for images (MRI.ui.w.imageView);
                             .well-title (small caps label), .well-readout (mono status line)
     .scope                  near-black canvas background for any canvas
     .image-grid             auto-fit grid of wells, min 220px (--min to change)
     .plot                   MRI.ui.w.plot container; .plot-scope dark variant;
                             .plot-framed gives a card frame
     .caption                small centred caption under a figure
     .empty                  dashed "nothing yet" placeholder
     .error-card             failure message with optional details

   DISCLOSURE
     details.adv             the "Advanced" section: <details class="adv">
                             <summary>Advanced</summary> ...content... </details>

   UTILITIES
     .muted .faint .good .warn .bad .accent (text colours), .sr-only,
     .nowrap, .center, .right, .mt-0 .mt-1 .mt-2 .mb-0 .mb-1 .mb-2,
     .hidden (display: none)
   ============================================================ */

/* ---------- tokens: light ---------- */
:root {
    color-scheme: light;
    --bg: #f4f6f9;
    --card: #ffffff;
    --card-2: #f7f8fa;
    --hover: rgba(15, 23, 42, 0.05);
    --fg: #161b22;
    --muted: #586170;
    --faint: #8a93a2;
    --border: #dde2e9;
    --border-strong: #c5ccd6;
    --border-subtle: #ebeef2;
    --grid: #e8ebf0;
    --axis: #a9b1bd;
    --track: #d6dbe3;

    --accent: #2563eb;
    --accent-strong: #2563eb;
    --accent-strong-hover: #1d4ed8;
    --accent-soft: rgba(37, 99, 235, 0.08);
    --accent-border: rgba(37, 99, 235, 0.28);
    --accent-ink: #1d4ed8;
    --on-accent: #ffffff;
    --focus: #2563eb;
    --focus-ring: rgba(37, 99, 235, 0.35);

    --good: #15803d;
    --good-ink: #166534;      /* #15803d on its own tint measured 4.49:1 in a panel; this is above 6:1 */
    --good-soft: rgba(22, 163, 74, 0.10);
    --good-border: rgba(22, 163, 74, 0.32);
    --warn: #b45309;
    --warn-soft: rgba(217, 119, 6, 0.10);
    --warn-border: rgba(217, 119, 6, 0.35);
    --bad: #b91c1c;
    --bad-soft: rgba(220, 38, 38, 0.08);
    --bad-border: rgba(220, 38, 38, 0.32);

    --scope-bg: #0b0f17;
    --scope-fg: #d6dde8;
    --scope-muted: #8794a8;
    --scope-grid: #1c2536;
    --scope-axis: #3a4760;
    --scope-border: #0b0f17;

    --c1: #2a78d6; --c2: #eb6834; --c3: #1baf7a; --c4: #eda100;
    --c5: #e87ba4; --c6: #008300; --c7: #6250d6; --c8: #e34948;
    /* Scope series: the validated dark-surface steps (checked against #0b0f17
       and #05080f: lightness band, CVD separation and 3:1 contrast all pass). */
    --sc1: #3987e5; --sc2: #d95926; --sc3: #199e70; --sc4: #c98500;
    --sc5: #d55181; --sc6: #008300; --sc7: #9085e9; --sc8: #e66767;

    --seq-rf: #d9541e;
    --seq-gx: #2a78d6;
    --seq-gy: #0f9a6a;
    --seq-gz: #6250d6;
    --seq-adc: #b7791f;

    --code-bg: rgba(15, 23, 42, 0.06);
    --toast-bg: #1b2333;
    --tip-bg: rgba(255, 255, 255, 0.97);
    --tip-fg: #161b22;
    --console-bg: rgba(255, 255, 255, 0.92);

    --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
    --font-mono: ui-monospace, SFMono-Regular, Menlo, Consolas, "Liberation Mono", monospace;
    --font-math: "Cambria Math", "STIX Two Math", "Latin Modern Math", Cambria, "Times New Roman", serif;

    --radius: 10px;
    --radius-sm: 6px;
    --ctl-h: 32px;
    --gutter: 16px;
    --maxw: 1280px;
    --console-h: 110px;
    --shadow-1: 0 1px 2px rgba(16, 24, 40, 0.05);
    --shadow-2: 0 6px 20px -6px rgba(16, 24, 40, 0.25), 0 2px 6px rgba(16, 24, 40, 0.08);
}

/* ---------- tokens: dark (system preference unless overridden, or forced) ---------- */
@media (prefers-color-scheme: dark) {
    :root:not([data-theme="light"]) {
        color-scheme: dark;
        --bg: #0b1220;
        --card: #121a2b;
        --card-2: #0f1626;
        --hover: rgba(148, 163, 184, 0.08);
        --fg: #e5e9f0;
        --muted: #9aa8bc;
        --faint: #6b7a90;
        --border: #243049;
        --border-strong: #34425f;
        --border-subtle: #1b2538;
        --grid: #1e293b;
        --axis: #3d4a63;
        --track: #2c3a55;
        --accent: #60a5fa;
        --accent-strong: #2563eb;
        --accent-strong-hover: #3b82f6;
        --accent-soft: rgba(96, 165, 250, 0.10);
        --accent-border: rgba(96, 165, 250, 0.30);
        --accent-ink: #60a5fa;
        --on-accent: #ffffff;
        --focus: #60a5fa;
        --focus-ring: rgba(96, 165, 250, 0.40);
        --good: #4ade80;
        --good-ink: #4ade80;
        --good-soft: rgba(74, 222, 128, 0.10);
        --good-border: rgba(74, 222, 128, 0.30);
        --warn: #fbbf24;
        --warn-soft: rgba(251, 191, 36, 0.10);
        --warn-border: rgba(251, 191, 36, 0.30);
        --bad: #f87171;
        --bad-soft: rgba(248, 113, 113, 0.10);
        --bad-border: rgba(248, 113, 113, 0.32);
        --scope-bg: #05080f;
        --scope-border: #1f2a40;
        --c1: #3987e5; --c2: #d95926; --c3: #199e70; --c4: #c98500;
        --c5: #d55181; --c6: #008300; --c7: #9085e9; --c8: #e66767;
        --seq-rf: #f07a45;
        --seq-gx: #5a9ff0;
        --seq-gy: #2fc28c;
        --seq-gz: #a39af0;
        --seq-adc: #f0b429;
        --code-bg: rgba(148, 163, 184, 0.12);
        --toast-bg: #1e293b;
        --tip-bg: rgba(15, 22, 38, 0.97);
        --tip-fg: #e5e9f0;
        --console-bg: rgba(18, 26, 43, 0.92);
        --shadow-1: 0 1px 2px rgba(0, 0, 0, 0.3);
        --shadow-2: 0 8px 24px -8px rgba(0, 0, 0, 0.6), 0 2px 6px rgba(0, 0, 0, 0.3);
    }
}
:root[data-theme="dark"] {
    color-scheme: dark;
    --bg: #0b1220;
    --card: #121a2b;
    --card-2: #0f1626;
    --hover: rgba(148, 163, 184, 0.08);
    --fg: #e5e9f0;
    --muted: #9aa8bc;
    --faint: #6b7a90;
    --border: #243049;
    --border-strong: #34425f;
    --border-subtle: #1b2538;
    --grid: #1e293b;
    --axis: #3d4a63;
    --track: #2c3a55;
    --accent: #60a5fa;
    --accent-strong: #2563eb;
    --accent-strong-hover: #3b82f6;
    --accent-soft: rgba(96, 165, 250, 0.10);
    --accent-border: rgba(96, 165, 250, 0.30);
    --accent-ink: #60a5fa;
    --on-accent: #ffffff;
    --focus: #60a5fa;
    --focus-ring: rgba(96, 165, 250, 0.40);
    --good: #4ade80;
    --good-ink: #4ade80;
    --good-soft: rgba(74, 222, 128, 0.10);
    --good-border: rgba(74, 222, 128, 0.30);
    --warn: #fbbf24;
    --warn-soft: rgba(251, 191, 36, 0.10);
    --warn-border: rgba(251, 191, 36, 0.30);
    --bad: #f87171;
    --bad-soft: rgba(248, 113, 113, 0.10);
    --bad-border: rgba(248, 113, 113, 0.32);
    --scope-bg: #05080f;
    --scope-border: #1f2a40;
    --c1: #3987e5; --c2: #d95926; --c3: #199e70; --c4: #c98500;
    --c5: #d55181; --c6: #008300; --c7: #9085e9; --c8: #e66767;
    --seq-rf: #f07a45;
    --seq-gx: #5a9ff0;
    --seq-gy: #2fc28c;
    --seq-gz: #a39af0;
    --seq-adc: #f0b429;
    --code-bg: rgba(148, 163, 184, 0.12);
    --toast-bg: #1e293b;
    --tip-bg: rgba(15, 22, 38, 0.97);
    --tip-fg: #e5e9f0;
    --console-bg: rgba(18, 26, 43, 0.92);
    --shadow-1: 0 1px 2px rgba(0, 0, 0, 0.3);
    --shadow-2: 0 8px 24px -8px rgba(0, 0, 0, 0.6), 0 2px 6px rgba(0, 0, 0, 0.3);
}

/* ---------- base ---------- */
*, *::before, *::after { box-sizing: border-box; }
html {
    -webkit-text-size-adjust: 100%; text-size-adjust: 100%;
    /* Focus moves and scripted scrolls stop below the sticky console (WCAG 2.4.11).
       This is for content: app.js keeps focus moves onto the console's own
       controls (always on screen) from scrolling the page. */
    scroll-padding-top: calc(var(--console-h, 110px) + 12px);
}
body {
    margin: 0;
    background: var(--bg);
    color: var(--fg);
    font-family: var(--font-sans);
    font-size: 15px;
    line-height: 1.5;
    overflow-x: hidden;
}
h1, h2, h3, h4 { line-height: 1.25; margin: 0 0 0.5em; font-weight: 650; }
h2 { font-size: 1.15rem; }
h3 { font-size: 1rem; }
h4 { font-size: 0.9rem; }
p { margin: 0 0 0.75em; }
a { color: var(--accent); text-underline-offset: 2px; }
a:hover { text-decoration-thickness: 2px; }
img, svg, canvas { max-width: 100%; }
code, kbd, pre, .mono { font-family: var(--font-mono); }
code { font-size: 0.86em; background: var(--code-bg); padding: 1px 5px; border-radius: 4px; }
pre { font-size: 0.82rem; overflow-x: auto; background: var(--card-2); border: 1px solid var(--border); border-radius: var(--radius-sm); padding: 10px 12px; margin: 0 0 0.75em; }
pre code { background: none; padding: 0; }
kbd, .kbd {
    font-size: 0.78em; padding: 1px 6px; border-radius: 4px;
    border: 1px solid var(--border-strong); border-bottom-width: 2px; background: var(--card); color: var(--fg);
}
hr { border: 0; border-top: 1px solid var(--border); margin: 16px 0; }
::selection { background: var(--accent-soft); }

:focus { outline: none; }
:focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; border-radius: 4px; }

.sr-only {
    position: absolute !important; width: 1px; height: 1px; padding: 0; margin: -1px;
    overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; border: 0;
}
.skip-link {
    position: absolute; left: 16px; top: -48px; z-index: 200; padding: 8px 14px;
    background: var(--accent-strong); color: var(--on-accent); border-radius: var(--radius-sm); text-decoration: none;
}
.skip-link:focus { top: 8px; }
.hidden, [hidden] { display: none !important; }

.wrap { max-width: var(--maxw); margin: 0 auto; padding-left: var(--gutter); padding-right: var(--gutter); }

/* ---------- header ---------- */
.app-header { background: var(--card); border-bottom: 1px solid var(--border); }
.app-header .wrap { padding-top: 10px; padding-bottom: 12px; }
.back-link {
    display: inline-flex; align-items: center; gap: 4px;
    color: var(--muted); text-decoration: none; font-size: 0.84rem;
}
.back-link:hover { color: var(--accent); }
.title-row { display: flex; align-items: center; gap: 12px; margin-top: 6px; }
.brand { display: flex; align-items: center; gap: 12px; min-width: 0; flex: 1; }
.brand-mark { width: 38px; height: 38px; flex: none; }
.brand-text { min-width: 0; }
.brand h1 { font-size: 1.45rem; margin: 0; letter-spacing: -0.01em; }
.subtitle { margin: 2px 0 0; color: var(--muted); font-size: 0.9rem; line-height: 1.35; }
.header-tools { display: flex; align-items: center; gap: 8px; flex: none; }
.badge-field { font-family: var(--font-mono); font-weight: 600; letter-spacing: 0; }
.theme-toggle .theme-icon { display: none; width: 16px; height: 16px; }
.theme-toggle[data-mode="auto"] .ti-auto,
.theme-toggle[data-mode="light"] .ti-light,
.theme-toggle[data-mode="dark"] .ti-dark { display: block; }

/* ---------- sticky console: scan bar + tab bar ---------- */
.console {
    position: sticky; top: 0; z-index: 50;
    background: var(--card);
    background: var(--console-bg);
    -webkit-backdrop-filter: saturate(1.4) blur(10px);
    backdrop-filter: saturate(1.4) blur(10px);
    border-bottom: 1px solid var(--border);
    box-shadow: 0 6px 16px -14px rgba(0, 0, 0, 0.45);
}
.scanbar { position: relative; border-bottom: 1px solid var(--border-subtle); }
.scanbar-inner {
    display: grid;
    grid-template-columns: auto minmax(0, 1fr) auto;
    grid-template-areas: "actions status thumbs";
    align-items: center;
    gap: 8px 18px;
    padding-top: 9px; padding-bottom: 9px;
}
.scan-actions { grid-area: actions; display: flex; align-items: center; flex-wrap: wrap; gap: 8px; }
.scan-status { grid-area: status; min-width: 0; }
.scan-thumbs { grid-area: thumbs; display: flex; gap: 8px; }
.btn-acquire { min-width: 112px; }
.btn-acquire svg, .btn-stop svg { width: 12px; height: 12px; flex: none; }
.scan-speed { display: inline-flex; align-items: center; gap: 6px; font-size: 0.8rem; color: var(--muted); }
.scan-speed .select { height: 30px; }
/* On the Spectroscopy tab the bar runs the spectrum (app.js adds .is-spectro):
   playback speed and automatic re-scans are imaging settings, so they step aside. */
.scanbar.is-spectro .scan-speed, .scanbar.is-spectro .scan-actions > .toggle { display: none; }
.scan-line { display: flex; align-items: center; gap: 8px; min-width: 0; font-size: 0.84rem; }
.scan-state { font-weight: 650; white-space: nowrap; font-variant-numeric: tabular-nums; }
.scan-pct { font-weight: 650; font-variant-numeric: tabular-nums; margin-left: -4px; white-space: nowrap; }
.scan-pct:empty { display: none; }
.scan-msg {
    min-width: 0; flex: 1; overflow: hidden; text-overflow: ellipsis; white-space: nowrap;
    color: var(--muted);
}
.scan-msg[data-kind="bad"] { color: var(--bad); font-weight: 600; }
.scan-msg[data-kind="warn"] { color: var(--warn); font-weight: 600; }
.scan-msg[data-kind="good"] { color: var(--good); }
/* A problem may need two lines; the rest of the text stays in the title. */
.scan-msg[data-kind="bad"], .scan-msg[data-kind="warn"] {
    white-space: normal; display: -webkit-box; -webkit-line-clamp: 2; line-clamp: 2; -webkit-box-orient: vertical;
    line-height: 1.3;
}
/* The action sits beside the message, never inside its ellipsis. */
.scan-action { flex: none; display: inline-flex; }
.scan-action-btn { color: var(--accent-ink); border-color: var(--accent-border); white-space: nowrap; }
.scan-summary {
    font-family: var(--font-mono); font-size: 0.78rem; color: var(--muted);
    white-space: nowrap; overflow: hidden; text-overflow: ellipsis; margin-top: 2px;
}
.scan-summary .sum-bad { color: var(--bad); font-weight: 600; }
.scan-summary .sum-name { color: var(--fg); font-weight: 600; }
.scan-summary .sum-stale { color: var(--warn); }
.linklike {
    background: none; border: 0; padding: 0; font: inherit; color: var(--accent); cursor: pointer;
    text-decoration: underline; text-underline-offset: 2px;
}

/* Status light: idle, busy (pulsing), done, warn, error. */
.led {
    width: 9px; height: 9px; border-radius: 50%; flex: none;
    background: var(--faint); box-shadow: 0 0 0 3px rgba(138, 147, 162, 0.18);
}
.led[data-state="busy"] { background: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); animation: led-pulse 1s ease-in-out infinite; }
.led[data-state="done"] { background: var(--good); box-shadow: 0 0 0 3px var(--good-soft); }
.led[data-state="warn"] { background: var(--warn); box-shadow: 0 0 0 3px var(--warn-soft); }
.led[data-state="error"] { background: var(--bad); box-shadow: 0 0 0 3px var(--bad-soft); }
@keyframes led-pulse { 50% { opacity: 0.35; } }

/* The progress bar is a hairline along the bottom edge of the scan bar. */
.scan-progress { position: absolute; left: 0; right: 0; bottom: -1px; height: 3px; background: transparent; overflow: hidden; }
.scan-progress-fill {
    height: 100%; width: 0; background: var(--accent);
    transition: width 0.12s linear, opacity 0.4s ease;
}
.scan-progress[data-stage="compute"] .scan-progress-fill {
    background-image: repeating-linear-gradient(-45deg, rgba(255, 255, 255, 0.35) 0 6px, transparent 6px 12px);
    background-size: 17px 17px; animation: stripes 0.6s linear infinite;
}
.scan-progress[data-stage="done"] .scan-progress-fill { opacity: 0; }
@keyframes stripes { to { background-position: 17px 0; } }

/* Thumbnails: tiny k-space and image wells that jump to their tabs. */
.thumb {
    position: relative; width: 50px; height: 50px; padding: 0; border-radius: 7px; overflow: hidden;
    background: var(--scope-bg); border: 1px solid var(--border-strong); cursor: pointer; flex: none;
}
.thumb canvas { display: block; width: 100%; height: 100%; }
.thumb-label {
    position: absolute; left: 0; right: 0; bottom: 0; padding: 6px 3px 1px;
    font-size: 0.6rem; font-weight: 600; letter-spacing: 0.03em; color: #e2e8f0; text-align: center;
    background: linear-gradient(transparent, rgba(0, 0, 0, 0.75));
}
.thumb:hover { border-color: var(--accent); }
.thumb.stale canvas { opacity: 0.45; }

/* Tab bar */
.tabbar .wrap { padding-top: 0; padding-bottom: 0; }
.tablist {
    display: flex; gap: 2px; overflow-x: auto; overscroll-behavior-x: contain;
    scrollbar-width: none; -ms-overflow-style: none;
    margin: 0 calc(-1 * var(--gutter)); padding: 0 var(--gutter);
}
.tablist::-webkit-scrollbar { display: none; }
.tab {
    appearance: none; -webkit-appearance: none; background: none; border: 0;
    border-bottom: 2px solid transparent;
    padding: 10px 13px 9px; margin: 0;
    font: 600 0.86rem/1.2 var(--font-sans); color: var(--muted);
    white-space: nowrap; cursor: pointer; border-radius: 6px 6px 0 0;
    display: inline-flex; align-items: center; gap: 6px; flex: none;
}
.tab:hover { color: var(--fg); background: var(--hover); }
.tab[aria-selected="true"] { color: var(--accent); border-bottom-color: var(--accent); }
.tab:focus-visible { outline-offset: -3px; }
.tab .tab-flag { width: 6px; height: 6px; border-radius: 50%; background: var(--warn); }

/* Lesson strip: the lesson in progress, under the tab bar (MRI.ui.lessonStrip). */
.lesson-strip { border-top: 1px solid var(--border-subtle); background: var(--accent-soft); }
.lesson-strip-inner { display: flex; align-items: center; gap: 8px; padding-top: 5px; padding-bottom: 5px; font-size: 0.82rem; }
.lesson-strip-title { flex: 1; min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; font-weight: 600; color: var(--fg); }
.lesson-strip-back { flex: none; color: var(--accent-ink); border-color: var(--accent-border); }
.lesson-strip-close {
    flex: none; appearance: none; border: 0; background: none; color: var(--muted); cursor: pointer;
    width: 28px; height: 28px; border-radius: 6px; font-size: 1.1rem; line-height: 1;
}
.lesson-strip-close:hover { color: var(--fg); background: var(--hover); }

/* ---------- main area ---------- */
.panels { padding-top: 20px; padding-bottom: 40px; }
.tab-panel { min-width: 0; }
.tab-panel:focus-visible { outline-offset: 6px; }
.boot-msg { padding: 32px 0; color: var(--muted); text-align: center; }
.boot-msg.is-error { color: var(--bad); }
.app-footer { color: var(--muted); font-size: 0.78rem; text-align: center; padding: 8px 0 28px; }
.noscript-note { margin: 24px auto; max-width: 640px; }

/* ---------- layout primitives ---------- */
.panel {
    background: var(--card); border: 1px solid var(--border); border-radius: var(--radius);
    padding: 16px 18px; margin: 0 0 16px; box-shadow: var(--shadow-1); min-width: 0;
}
.panel > :last-child { margin-bottom: 0; }
.panel-flush { padding: 0; overflow: hidden; }
.panel-head { display: flex; align-items: center; flex-wrap: wrap; gap: 6px 12px; margin: 0 0 12px; }
.panel-title { font-size: 0.98rem; font-weight: 650; margin: 0; }
.panel-sub { color: var(--muted); font-size: 0.82rem; }
.panel-head > .spacer { flex: 1; }
.grid {
    display: grid; gap: var(--gap, 16px);
    grid-template-columns: repeat(auto-fit, minmax(min(100%, var(--min, 260px)), 1fr));
}
.grid > *, .grid-2 > *, .grid-3 > *, .split > *, .split-even > * { min-width: 0; }
.grid-2 { display: grid; gap: 16px; grid-template-columns: repeat(2, minmax(0, 1fr)); }
.grid-3 { display: grid; gap: 16px; grid-template-columns: repeat(3, minmax(0, 1fr)); }
.split { display: grid; gap: 16px; grid-template-columns: minmax(0, 1fr) minmax(260px, 340px); align-items: start; }
.split-even { display: grid; gap: 16px; grid-template-columns: repeat(2, minmax(0, 1fr)); align-items: start; }
.row { display: flex; flex-wrap: wrap; align-items: center; gap: 8px 12px; }
.stack { display: flex; flex-direction: column; gap: 12px; }
.stack-sm { gap: 6px; }
.stack-lg { gap: 20px; }
.spacer { flex: 1; }
.toolbar { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-bottom: 12px; }
@media (max-width: 1000px) { .grid-3 { grid-template-columns: repeat(2, minmax(0, 1fr)); } }
@media (max-width: 900px) { .split { grid-template-columns: minmax(0, 1fr); } }
@media (max-width: 760px) { .grid-2, .split-even { grid-template-columns: minmax(0, 1fr); } }
@media (max-width: 640px) { .grid-3 { grid-template-columns: minmax(0, 1fr); } }

/* ---------- concept card ---------- */
.concept {
    background: linear-gradient(var(--accent-soft), var(--accent-soft)), var(--card);
    border: 1px solid var(--accent-border); border-left: 3px solid var(--accent);
    border-radius: var(--radius); margin: 0 0 16px;
}
.concept-head {
    list-style: none; cursor: pointer; display: flex; align-items: baseline; flex-wrap: wrap; gap: 4px 10px;
    padding: 12px 40px 12px 16px; position: relative; border-radius: var(--radius);
}
.concept-head::-webkit-details-marker { display: none; }
.concept-head::after {
    content: ""; position: absolute; right: 16px; top: 17px; width: 7px; height: 7px;
    border-right: 2px solid var(--muted); border-bottom: 2px solid var(--muted);
    transform: rotate(45deg); transition: transform 0.15s ease;
}
.concept:not([open]) > .concept-head::after { transform: rotate(-45deg); }
.concept-eyebrow {
    font-size: 0.66rem; font-weight: 700; letter-spacing: 0.09em; text-transform: uppercase; color: var(--accent);
}
.concept-title { font-size: 1.02rem; font-weight: 650; margin: 0; line-height: 1.3; display: inline; }
.concept-title:focus { outline: none; }
.concept-title:focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; }
/* Folded: eyebrow, title and the formula on one line. */
.concept-peek { display: none; }
.concept:not([open]) > .concept-head { flex-wrap: nowrap; align-items: baseline; }
.concept:not([open]) > .concept-head > .concept-title { flex: none; max-width: 70%; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; display: block; }
.concept:not([open]) > .concept-head > .concept-peek {
    display: block; flex: 1 1 0; min-width: 0; white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
    font-family: var(--font-math); font-size: 0.95rem; color: var(--muted);
}
.concept-peek * { display: inline !important; margin: 0 !important; padding: 0 !important; border: 0 !important; background: none !important; }
.concept-peek br { display: none !important; }
@media (max-width: 520px) {
    .concept:not([open]) > .concept-head { flex-wrap: wrap; }
    .concept:not([open]) > .concept-head > .concept-title { max-width: 100%; white-space: normal; }
    .concept:not([open]) > .concept-head > .concept-peek { flex-basis: 100%; }
}
.concept-content {
    display: grid; grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr); gap: 12px 28px; padding: 0 16px 14px;
}
.concept-content-single { grid-template-columns: minmax(0, 1fr); }
.concept-body { font-size: 0.9rem; line-height: 1.6; }
.concept-body > :last-child { margin-bottom: 0; }
.concept-formula {
    font-family: var(--font-math); font-size: 1.08rem; text-align: center;
    background: var(--card); border: 1px solid var(--border); border-radius: 8px;
    padding: 8px 12px; margin-top: 10px; overflow-x: auto;
}
.concept-try-title {
    font-size: 0.7rem; font-weight: 700; letter-spacing: 0.08em; text-transform: uppercase; color: var(--muted); margin-bottom: 6px;
}
.concept-try-list { list-style: none; margin: 0; padding: 0; counter-reset: try; font-size: 0.86rem; line-height: 1.5; }
.concept-try-list li { counter-increment: try; position: relative; padding-left: 28px; margin-bottom: 7px; }
.concept-run { margin-left: 2px; vertical-align: 1px; color: var(--accent); border-color: var(--accent-border); background: var(--card); }
.concept-run:hover { background: var(--accent-soft); border-color: var(--accent); }
.concept-try-list li::before {
    content: counter(try); position: absolute; left: 0; top: 1px; width: 19px; height: 19px; border-radius: 50%;
    display: grid; place-items: center; font-size: 0.7rem; font-weight: 700;
    background: var(--card); color: var(--accent); border: 1px solid var(--accent-border);
}
@media (max-width: 760px) {
    .concept-content { grid-template-columns: minmax(0, 1fr); }
}

/* ---------- callouts and notes ---------- */
.callout {
    background: var(--accent-soft); border: 1px solid var(--accent-border); border-radius: 8px;
    padding: 10px 12px; font-size: 0.86rem; line-height: 1.5; margin: 0 0 12px;
}
.callout > :last-child { margin-bottom: 0; }
.callout-warn { background: var(--warn-soft); border-color: var(--warn-border); }
.callout-bad { background: var(--bad-soft); border-color: var(--bad-border); }
.callout-good { background: var(--good-soft); border-color: var(--good-border); }
.note { font-size: 0.84rem; color: var(--muted); line-height: 1.5; }
.note strong { color: var(--fg); }
.simplification {
    font-size: 0.82rem; font-style: italic; color: var(--muted);
    border-left: 2px dotted var(--border-strong); padding-left: 10px; margin: 8px 0;
}

/* ---------- buttons ---------- */
.btn, button:not([class]) {
    display: inline-flex; align-items: center; justify-content: center; gap: 6px;
    height: var(--ctl-h); padding: 0 13px; border-radius: var(--radius-sm);
    border: 1px solid var(--border-strong); background: var(--card); color: var(--fg);
    font: 600 0.85rem/1 var(--font-sans); white-space: nowrap; cursor: pointer; text-decoration: none;
    transition: background-color 0.12s ease, border-color 0.12s ease, color 0.12s ease, box-shadow 0.12s ease;
    -webkit-tap-highlight-color: transparent;
}
.btn:hover, button:not([class]):hover { background: var(--card-2); border-color: var(--axis); }
.btn:active { transform: translateY(0.5px); }
.btn:focus-visible, button:not([class]):focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; }
.btn:disabled, .btn[aria-disabled="true"], button:not([class]):disabled { opacity: 0.5; cursor: not-allowed; transform: none; }
.btn-primary { background: var(--accent-strong); border-color: var(--accent-strong); color: var(--on-accent); }
.btn-primary:hover { background: var(--accent-strong-hover); border-color: var(--accent-strong-hover); }
.btn-ghost { background: transparent; border-color: transparent; color: var(--fg); }
.btn-ghost:hover { background: var(--hover); border-color: transparent; }
.btn-danger { color: var(--bad); }
.btn-danger:hover { background: var(--bad-soft); border-color: var(--bad-border); }
.btn-sm { height: 28px; padding: 0 10px; font-size: 0.8rem; }
.btn-xs { height: 24px; padding: 0 8px; font-size: 0.74rem; border-radius: 5px; }   /* 24 px: the WCAG 2.5.8 minimum */
.btn-block { display: flex; width: 100%; }
.btn-icon { display: inline-flex; }
.btn-icon svg { width: 14px; height: 14px; }
.btn-group { display: inline-flex; }
.btn-group > .btn { border-radius: 0; }
.btn-group > .btn + .btn { margin-left: -1px; }
.btn-group > .btn:first-child { border-radius: var(--radius-sm) 0 0 var(--radius-sm); }
.btn-group > .btn:last-child { border-radius: 0 var(--radius-sm) var(--radius-sm) 0; }

/* ---------- form controls ---------- */
select, .select {
    appearance: none; -webkit-appearance: none;
    height: var(--ctl-h); max-width: 100%; padding: 0 30px 0 10px; border-radius: var(--radius-sm);
    border: 1px solid var(--border-strong); color: var(--fg); font: 500 0.86rem var(--font-sans); cursor: pointer;
    background-color: var(--card);
    background-image: linear-gradient(45deg, transparent 50%, var(--muted) 50%), linear-gradient(135deg, var(--muted) 50%, transparent 50%);
    background-position: calc(100% - 15px) 52%, calc(100% - 10px) 52%;
    background-size: 5px 5px, 5px 5px; background-repeat: no-repeat;
}
select:hover, .select:hover { border-color: var(--axis); }
select:disabled { opacity: 0.55; cursor: not-allowed; }
.select-sm { height: 28px; font-size: 0.8rem; }
.input, input[type="number"], input[type="text"]:not(.ctl-num), input[type="search"], textarea {
    height: var(--ctl-h); padding: 0 10px; border-radius: var(--radius-sm);
    border: 1px solid var(--border-strong); background: var(--card); color: var(--fg);
    font: 0.86rem var(--font-sans); min-width: 0; max-width: 100%;
}
textarea { height: auto; padding: 8px 10px; line-height: 1.45; }
.input:focus-visible, input[type="number"]:focus-visible, input[type="text"]:focus-visible, textarea:focus-visible, select:focus-visible {
    outline: none; border-color: var(--focus); box-shadow: 0 0 0 3px var(--focus-ring);
}
input[type="checkbox"], input[type="radio"] { accent-color: var(--accent-strong); }
.check { display: inline-flex; align-items: center; gap: 7px; font-size: 0.86rem; cursor: pointer; }
.check input { margin: 0; width: 15px; height: 15px; }

/* Range inputs: styled globally so every slider in every tab matches.
   --fill (a percentage, set by MRI.ui.w.slider) colours the part of the
   track below the thumb. */
input[type="range"] {
    -webkit-appearance: none; appearance: none; display: block;
    width: 100%; height: 22px; margin: 0; background: transparent; cursor: pointer; --fill: 0%;
}
input[type="range"]::-webkit-slider-runnable-track {
    height: 4px; border-radius: 2px;
    background: linear-gradient(to right, var(--accent) 0, var(--accent) var(--fill), var(--track) var(--fill), var(--track) 100%);
}
input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none; appearance: none; width: 16px; height: 16px; margin-top: -6px; border-radius: 50%;
    background: var(--card); border: 2px solid var(--accent); box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
    transition: box-shadow 0.12s ease;
}
input[type="range"]::-moz-range-track { height: 4px; border-radius: 2px; background: var(--track); }
input[type="range"]::-moz-range-progress { height: 4px; border-radius: 2px; background: var(--accent); }
input[type="range"]::-moz-range-thumb {
    width: 12px; height: 12px; border-radius: 50%; background: var(--card); border: 2px solid var(--accent);
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.25);
}
input[type="range"]:hover::-webkit-slider-thumb { box-shadow: 0 0 0 4px var(--accent-soft), 0 1px 3px rgba(0, 0, 0, 0.25); }
input[type="range"]:focus-visible { outline: none; }
input[type="range"]:focus-visible::-webkit-slider-thumb { box-shadow: 0 0 0 4px var(--focus-ring); }
input[type="range"]:focus-visible::-moz-range-thumb { box-shadow: 0 0 0 4px var(--focus-ring); }
input[type="range"]:disabled { opacity: 0.45; cursor: not-allowed; }

/* Control rows (MRI.ui.w.slider / select / segmented). */
.controls {
    display: grid; gap: 12px 20px;
    grid-template-columns: repeat(auto-fill, minmax(min(100%, var(--min, 200px)), 1fr));
}
.ctl {
    display: grid; grid-template-columns: minmax(0, 1fr) auto; align-items: center;
    column-gap: 8px; row-gap: 3px; min-width: 0;
}
.ctl > :nth-child(n+3), .ctl-select > select, .ctl-seg > .seg { grid-column: 1 / -1; }
.ctl-select > select { width: 100%; }
.ctl-bare { display: block; }
.ctl-inline { display: flex; align-items: center; gap: 8px; }
.ctl-inline > select { width: auto; }
.ctl-label { font-size: 0.8rem; font-weight: 500; color: var(--muted); min-width: 0; overflow: hidden; text-overflow: ellipsis; }
.ctl-value {
    display: inline-flex; align-items: baseline; justify-content: flex-end; gap: 2px;
    font: 600 0.82rem var(--font-mono); font-variant-numeric: tabular-nums; color: var(--fg); white-space: nowrap;
}
output.ctl-value { color: var(--fg); }
.ctl-num {
    width: 6.5ch; padding: 1px 4px; margin: 0; border-radius: 4px; border: 1px solid transparent; background: transparent;
    font: inherit; color: var(--fg); text-align: right;
}
.ctl-num:hover { border-color: var(--border); background: var(--card-2); }
.ctl-num:focus { outline: none; border-color: var(--focus); box-shadow: 0 0 0 3px var(--focus-ring); background: var(--card); }
.ctl-unit { color: var(--muted); font-weight: 500; font-family: var(--font-sans); font-size: 0.78rem; }
.ctl.is-disabled .ctl-label, .ctl.is-disabled .ctl-value { opacity: 0.55; }

/* Toggle switch */
.toggle { position: relative; display: inline-flex; align-items: center; gap: 8px; cursor: pointer; font-size: 0.85rem; user-select: none; -webkit-user-select: none; }
.toggle input { position: absolute; opacity: 0; width: 1px; height: 1px; margin: 0; pointer-events: none; }
.toggle-track {
    position: relative; width: 32px; height: 18px; border-radius: 9px; flex: none;
    background: var(--track); transition: background-color 0.15s ease; border: 1px solid transparent;
}
.toggle-track::after {
    content: ""; position: absolute; top: 2px; left: 2px; width: 12px; height: 12px; border-radius: 50%;
    background: #fff; box-shadow: 0 1px 2px rgba(0, 0, 0, 0.3); transition: transform 0.15s ease;
}
.toggle input:checked + .toggle-track { background: var(--accent-strong); }
.toggle input:checked + .toggle-track::after { transform: translateX(14px); }
.toggle input:focus-visible + .toggle-track { outline: 2px solid var(--focus); outline-offset: 2px; }
.toggle.is-disabled { opacity: 0.5; cursor: not-allowed; }
.toggle-label { color: var(--fg); }

/* Segmented control */
.seg {
    display: inline-flex; max-width: 100%; overflow-x: auto; scrollbar-width: none;
    padding: 2px; gap: 2px; border-radius: 8px; background: var(--card-2); border: 1px solid var(--border);
}
.seg::-webkit-scrollbar { display: none; }
.seg > button {
    appearance: none; -webkit-appearance: none; border: 0; background: transparent; color: var(--muted);
    height: 26px; padding: 0 11px; border-radius: 6px; font: 600 0.8rem/1 var(--font-sans); white-space: nowrap; cursor: pointer; flex: none;
}
.seg > button:hover { color: var(--fg); }
.seg > button[aria-checked="true"] { background: var(--card); color: var(--fg); box-shadow: 0 0 0 1px var(--border-strong), 0 1px 2px rgba(0, 0, 0, 0.12); }
.seg > button:focus-visible { outline: 2px solid var(--focus); outline-offset: 0; }
.seg > button:disabled { opacity: 0.45; cursor: not-allowed; }
.seg-sm > button { height: 24px; padding: 0 8px; font-size: 0.75rem; }
.ctl-seg > .seg { justify-self: start; }

/* ---------- data display ---------- */
.stat-table { width: 100%; border-collapse: collapse; font-size: 0.84rem; }
.stat-table caption { text-align: left; font-weight: 650; font-size: 0.82rem; padding-bottom: 6px; }
.stat-table th { text-align: left; font-weight: 500; color: var(--muted); padding: 5px 10px 5px 0; vertical-align: baseline; }
.stat-table td {
    text-align: right; font-family: var(--font-mono); font-size: 0.82rem; font-variant-numeric: tabular-nums;
    padding: 5px 0 5px 10px; vertical-align: baseline; overflow-wrap: anywhere;
}
.stat-table tr + tr > * { border-top: 1px solid var(--border-subtle); }
.stat-table .unit { color: var(--muted); font-family: var(--font-sans); font-size: 0.78rem; margin-left: 4px; }
.stat-table td.good { color: var(--good); }
.stat-table td.bad { color: var(--bad); }
.stat-table td.warn { color: var(--warn); }
.stat-table td.muted { color: var(--muted); }
.stat-table-compact th, .stat-table-compact td { padding-top: 3px; padding-bottom: 3px; }

.stats { display: grid; gap: 8px; grid-template-columns: repeat(auto-fit, minmax(min(100%, 130px), 1fr)); }
.stat { background: var(--card-2); border: 1px solid var(--border-subtle); border-radius: 8px; padding: 8px 11px; min-width: 0; }
.stat-label { font-size: 0.68rem; font-weight: 600; letter-spacing: 0.05em; text-transform: uppercase; color: var(--muted); }
.stat-value { font: 650 1.12rem/1.3 var(--font-mono); font-variant-numeric: tabular-nums; overflow-wrap: anywhere; }
.stat-unit { font: 500 0.78rem var(--font-sans); color: var(--muted); margin-left: 3px; }
.stat-value.good { color: var(--good); } .stat-value.bad { color: var(--bad); } .stat-value.warn { color: var(--warn); }

.badge {
    display: inline-flex; align-items: center; gap: 4px; height: 20px; padding: 0 8px; border-radius: 999px;
    font: 600 0.72rem/1 var(--font-sans); white-space: nowrap;
    background: var(--card-2); color: var(--fg); border: 1px solid var(--border);
}
.badge-accent { background: var(--accent-soft); color: var(--accent-ink); border-color: var(--accent-border); }
.badge-good { background: var(--good-soft); color: var(--good-ink); border-color: var(--good-border); }
.badge-warn { background: var(--warn-soft); color: var(--warn); border-color: var(--warn-border); }
.badge-bad { background: var(--bad-soft); color: var(--bad); border-color: var(--bad-border); }
.badge-muted { color: var(--muted); }

.legend { display: flex; flex-wrap: wrap; align-items: center; gap: 4px 14px; font-size: 0.78rem; color: var(--muted); }
.legend-item { display: inline-flex; align-items: center; gap: 6px; white-space: nowrap; }
.swatch { display: inline-block; width: 10px; height: 10px; border-radius: 2px; flex: none; background: currentColor; }
.swatch-line { width: 16px; height: 0; border-radius: 0; background: none !important; border-top: 2px solid currentColor; }
.swatch-dash { border-top-style: dashed; }
.well .legend, .plot-scope .legend { color: var(--scope-muted); }

.num { font-variant-numeric: tabular-nums; }
.muted { color: var(--muted); } .faint { color: var(--faint); }
.good { color: var(--good); } .warn { color: var(--warn); } .bad { color: var(--bad); } .accent { color: var(--accent); }
.nowrap { white-space: nowrap; } .center { text-align: center; } .right { text-align: right; }
.mt-0 { margin-top: 0; } .mt-1 { margin-top: 8px; } .mt-2 { margin-top: 16px; }
.mb-0 { margin-bottom: 0; } .mb-1 { margin-bottom: 8px; } .mb-2 { margin-bottom: 16px; }

/* ---------- image wells and scopes ---------- */
.well {
    margin: 0; background: var(--scope-bg); color: var(--scope-fg);
    border: 1px solid var(--scope-border); border-radius: var(--radius); padding: 10px; min-width: 0;
    align-self: start;           /* in a grid row, do not stretch to a taller neighbour */
}
.well-title {
    display: flex; align-items: center; justify-content: space-between; gap: 8px;
    font-size: 0.7rem; font-weight: 700; letter-spacing: 0.07em; text-transform: uppercase;
    color: var(--scope-muted); margin: 0 0 8px;
}
.well-readout {
    margin-top: 8px; min-height: 1.35em; font: 0.74rem/1.35 var(--font-mono); color: var(--scope-muted);
    white-space: nowrap; overflow: hidden; text-overflow: ellipsis; font-variant-numeric: tabular-nums;
}
.scope, canvas.scope { background: var(--scope-bg); border-radius: 6px; }
.iv-stage { position: relative; display: flex; justify-content: center; align-items: center; min-height: 60px; }
.iv-canvas {
    display: block; border-radius: 3px; image-rendering: pixelated; cursor: crosshair;
    -webkit-user-select: none; user-select: none; -webkit-touch-callout: none;
}
.iv-canvas.wl { touch-action: none; }
/* On touch screens a swipe over an image scrolls the page; window/level
   waits for a long press (MRI.ui.w.imageView). */
@media (any-pointer: coarse) {
    .iv-canvas, .iv-canvas.wl { touch-action: pan-y pinch-zoom; }
}
.iv-canvas.iv-wl-active { outline: 2px solid var(--sc4, #c98500); outline-offset: 1px; }
.iv-canvas:focus-visible { outline: 2px solid var(--focus); outline-offset: 2px; }
.iv-foot { display: flex; align-items: center; gap: 8px; min-width: 0; margin-top: 8px; }
.iv-foot .well-readout { margin-top: 0; flex: 1; min-width: 0; }
.iv-foot-bare { justify-content: flex-end; }
.iv-reset {
    flex: none; appearance: none; height: 20px; padding: 0 7px; border-radius: 4px; cursor: pointer;
    font: 600 0.68rem/1 var(--font-sans); color: var(--scope-fg); background: rgba(255, 255, 255, 0.08);
    border: 1px solid var(--scope-axis);
}
.iv-reset:hover { background: rgba(255, 255, 255, 0.16); }
.iv-wl {
    position: absolute; top: 6px; right: 6px; padding: 2px 6px; border-radius: 4px;
    font: 0.68rem var(--font-mono); background: rgba(0, 0, 0, 0.65); color: #e2e8f0; pointer-events: none;
}
.iv-empty {
    position: absolute; inset: 0; display: grid; place-items: center; padding: 12px; text-align: center;
    font-size: 0.82rem; color: var(--scope-muted); pointer-events: none;
}
.iv-cbar { display: flex; align-items: center; gap: 8px; margin-top: 8px; font: 0.7rem var(--font-mono); color: var(--scope-muted); }
.iv-cbar-canvas { flex: 1; min-width: 40px; height: 8px; border-radius: 2px; image-rendering: auto; }
.image-grid {
    display: grid; gap: 12px;
    grid-template-columns: repeat(auto-fit, minmax(min(100%, var(--min, 220px)), 1fr));
}
.caption { font-size: 0.8rem; color: var(--muted); text-align: center; margin-top: 6px; }

/* Plots */
.plot { margin: 0; min-width: 0; position: relative; align-self: start; }
.plot-framed { background: var(--card); border: 1px solid var(--border); border-radius: var(--radius); padding: 10px 12px; }
.plot-scope { background: var(--scope-bg); color: var(--scope-fg); border: 1px solid var(--scope-border); border-radius: var(--radius); padding: 10px 12px; }
.plot-head { display: flex; flex-wrap: wrap; align-items: center; justify-content: space-between; gap: 4px 14px; margin-bottom: 6px; }
.plot-title { font-size: 0.82rem; font-weight: 650; }
.plot-scope .plot-title { color: var(--scope-fg); }
.plot-stage { position: relative; }
.plot-canvas { display: block; width: 100%; }
.plot-tip {
    position: absolute; z-index: 5; pointer-events: none; padding: 5px 8px; border-radius: 6px;
    background: var(--tip-bg); color: var(--tip-fg); border: 1px solid var(--border);
    font: 0.72rem/1.45 var(--font-mono); white-space: nowrap; box-shadow: var(--shadow-2);
}
.plot-tip .swatch { margin-right: 5px; vertical-align: -1px; }
.plot-tip-x { color: var(--muted); }

.empty {
    border: 1px dashed var(--border-strong); border-radius: var(--radius); padding: 24px 16px;
    text-align: center; color: var(--muted); font-size: 0.86rem;
}
.error-card {
    border: 1px solid var(--bad-border); background: var(--bad-soft); border-radius: var(--radius);
    padding: 14px 16px; margin: 0 0 16px;
}
.error-card-title { font-weight: 650; color: var(--bad); margin-bottom: 4px; }
.error-card-msg { font-size: 0.88rem; }
.error-card-details { margin-top: 8px; font-size: 0.8rem; }
.error-card-details summary { cursor: pointer; color: var(--muted); }
.error-card-details pre { margin-top: 6px; max-height: 220px; }

/* ---------- details: the "Advanced" disclosure ---------- */
details.adv {
    border: 1px solid var(--border); border-radius: 8px; background: var(--card-2);
    padding: 0 12px; margin: 12px 0 0;
}
details.adv > summary {
    list-style: none; cursor: pointer; display: flex; align-items: center; gap: 8px;
    margin: 0 -12px; padding: 8px 12px; font-size: 0.84rem; font-weight: 600; color: var(--fg); border-radius: 8px;
}
details.adv > summary::-webkit-details-marker { display: none; }
details.adv > summary::before {
    content: ""; width: 6px; height: 6px; flex: none; margin: 0 2px;
    border-right: 2px solid var(--muted); border-bottom: 2px solid var(--muted);
    transform: rotate(-45deg); transition: transform 0.15s ease;
}
details.adv[open] > summary::before { transform: rotate(45deg); }
details.adv > summary:hover { background: var(--hover); }
details.adv[open] { padding-bottom: 12px; }
details.adv[open] > summary { margin-bottom: 10px; border-bottom: 1px solid var(--border); border-radius: 8px 8px 0 0; }

/* Stale banner (MRI.ui.w.staleBanner) */
.stale-banner { display: flex; flex-wrap: wrap; align-items: center; gap: 6px 12px; }
.stale-banner-text { flex: 1 1 16em; min-width: 0; }

/* ---------- toasts ---------- */
.toasts {
    position: fixed; right: 16px; bottom: 16px; z-index: 300;
    display: flex; flex-direction: column; align-items: flex-end; gap: 8px;
    max-width: min(400px, calc(100vw - 32px)); pointer-events: none;
}
.toast {
    pointer-events: auto; display: flex; align-items: flex-start; gap: 10px;
    background: var(--toast-bg); color: #eef2f7; border-radius: 8px; border-left: 3px solid #60a5fa;
    padding: 10px 10px 10px 12px; font-size: 0.86rem; line-height: 1.45; box-shadow: var(--shadow-2);
    animation: toast-in 0.18s ease-out;
}
.toast-good { border-left-color: #4ade80; }
.toast-warn { border-left-color: #fbbf24; }
.toast-bad { border-left-color: #f87171; }
.toast-msg { flex: 1; min-width: 0; overflow-wrap: anywhere; }
.toast-close {
    appearance: none; border: 0; background: none; color: #94a3b8; cursor: pointer;
    font-size: 1.1rem; line-height: 1; padding: 0 2px; border-radius: 4px; min-width: 24px; min-height: 24px;
}
.toast-close:hover { color: #fff; }
.toast .linklike { color: #93c5fd; }
.toast-out { opacity: 0; transform: translateY(6px); transition: opacity 0.2s ease, transform 0.2s ease; }
@keyframes toast-in { from { opacity: 0; transform: translateY(8px); } }

/* ---------- responsive shell ---------- */
@media (max-width: 999px) {
    .scanbar-inner { grid-template-columns: minmax(0, 1fr) auto; grid-template-areas: "actions thumbs" "status status"; row-gap: 6px; }
}
@media (max-width: 720px) {
    .subtitle { font-size: 0.82rem; }
    .brand h1 { font-size: 1.2rem; }
    .brand-mark { width: 30px; height: 30px; }
    .badge-field { display: none; }
    .theme-toggle .theme-label { display: none; }
    .theme-toggle { width: var(--ctl-h); padding: 0; }
    .scan-speed-label { display: none; }
}
@media (max-width: 640px) {
    body { font-size: 14.5px; }
    .scanbar-inner { grid-template-columns: minmax(0, 1fr); grid-template-areas: "actions" "status"; }
    .scan-thumbs { display: none; }
    .btn-acquire { min-width: 0; }
    .scan-summary { white-space: normal; display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; }
    .panel { padding: 12px; }
    .tab { padding: 10px 11px 9px; font-size: 0.84rem; }
    .panels { padding-top: 14px; }
}
@media (max-width: 640px) {
    /* Fade the ends of the tab strip so it is obvious that it scrolls. */
    .tablist {
        -webkit-mask-image: linear-gradient(to right, transparent 0, #000 14px, #000 calc(100% - 22px), transparent 100%);
        mask-image: linear-gradient(to right, transparent 0, #000 14px, #000 calc(100% - 22px), transparent 100%);
    }
}
@media (max-width: 480px) {
    .scan-actions { gap: 6px; }
    .btn-acquire { padding: 0 12px; }
    .btn-stop { width: var(--ctl-h); padding: 0; }
    .btn-stop .btn-text { display: none; }
    .scan-speed .select { padding-right: 24px; }
    .scan-speed .select { background-position: calc(100% - 13px) 52%, calc(100% - 8px) 52%; }
}
@media (max-width: 400px) {
    .auto-label-long { display: none; }
}
/* On short landscape screens the console would eat the viewport: let it scroll away. */
@media (max-height: 520px) and (orientation: landscape) {
    .console { position: static; }
    :root { --console-h: 0px; }
}

/* Buttons inside panels may wrap rather than overflow a narrow screen
   (reflow at 320 px, WCAG 1.4.10); one-line buttons look as before. */
.panel .btn, .concept .btn {
    white-space: normal; height: auto; min-height: var(--ctl-h); line-height: 1.2;
    padding-top: 4px; padding-bottom: 4px; text-align: center;
}
.panel .btn-sm, .concept .btn-sm { min-height: 28px; padding-top: 3px; padding-bottom: 3px; }
.panel .btn-xs, .concept .btn-xs { min-height: 24px; padding-top: 2px; padding-bottom: 2px; }
@media (max-width: 640px) {
    .scan-line { flex-wrap: wrap; row-gap: 4px; }
    .scan-msg { flex: 1 1 12em; }
}
/* Segmented controls wrap on small phones, so every option stays visible. */
@media (max-width: 420px) {
    .seg { flex-wrap: wrap; overflow-x: visible; }
    .seg > button { flex: 1 1 auto; }
}

/* Touch screens: targets about 40 px tall (WCAG 2.5.8 asks for 24; touch
   guidelines for 40-44). Only the sticky console stays at 36 px, so it does
   not take more of a phone's screen. */
@media (pointer: coarse) {
    .btn, button:not([class]) { min-height: 40px; }
    .console .btn { min-height: 36px; }        /* keep the sticky console compact on a phone */
    .btn-sm, .btn-xs, .panel .btn-sm, .panel .btn-xs, .concept .btn-sm, .concept .btn-xs { min-height: 40px; height: auto; }
    .console .btn-sm, .console .btn-xs { min-height: 36px; }
    .seg > button, .seg-sm > button { min-height: 40px; height: auto; }
    .toggle { min-height: 40px; }
    .check { min-height: 40px; }
    .check input, input[type="checkbox"]:not([role="switch"]) { width: 22px; height: 22px; }
    select, .select, .select-sm, .scan-speed .select { min-height: 36px; }
    input[type="range"] { height: 32px; }
    .iv-reset { height: 32px; padding: 0 10px; font-size: 0.74rem; }
    .lesson-strip-close { width: 40px; height: 40px; }
    .toast-close { min-width: 40px; min-height: 40px; }
    .theme-toggle { min-width: 40px; }
    .linklike { padding-top: 4px; padding-bottom: 4px; }
}

@media (prefers-reduced-motion: reduce) {
    *, *::before, *::after { animation-duration: 0.001ms !important; animation-iteration-count: 1 !important; transition-duration: 0.001ms !important; }
}
@media (forced-colors: active) {
    .tab[aria-selected="true"] { border-bottom-color: Highlight; }
    .toggle-track, .led { forced-color-adjust: none; }
}