/* Cascade layer order — enforces specificity hierarchy across the package. */
@layer platform-ui.reset, platform-ui.tokens, platform-ui.grammar, platform-ui.primitives;


/*
 * Stacking order, named once.
 *
 * MEASURED before this existed: 25 z-index declarations across platform-ui,
 * semitexa-theme and semitexa-os carrying 13 distinct values — 60 used four
 * times, 57 and 40 twice each, and one 9999. Two numeric universes had grown
 * side by side: component-local values in the tens, and the behaviours layer in
 * the thousands, with nothing recording which was meant to win.
 *
 * These are NOT skin tokens and deliberately do not join the skin schema. A
 * skin owns how a surface looks; it does not get to decide whether a toast
 * appears above a modal. Colours there, order here.
 *
 * The numbers preserve the order already in force, so adopting them changes no
 * rendering. Gaps are kept between layers for the same reason the old numbers
 * had them: something will need to sit between two of these.
 */
@layer platform-ui.tokens {
    :root {
        --ui-z-base: 0;
        --ui-z-dropdown: 1000;
        --ui-z-backdrop: 1090;
        --ui-z-offcanvas: 1095;
        --ui-z-tooltip: 1100;
        --ui-z-toast: 1200;

        /*
         * Component-scoped overlays. These sit inside a component rather than
         * over the page, which is why their values are small — and why raising
         * them into the layers above would be a rendering change rather than a
         * rename. Left as they were and named, so the next person can see the
         * two universes instead of discovering them.
         */
        --ui-z-component-popover: 40;
        --ui-z-component-overlay: 20;
        /* A sticky header row inside a scrolling table: above its own cells only. */
        --ui-z-component-sticky: 1;
    }
}


/*
 * Foundation tokens — the scales every primitive and component is built on.
 *
 * A skin owns colour, radius, shadow and motion (semitexa/theme TokenContract).
 * It does not own rhythm: spacing, type scale and control heights are the same
 * under every skin, the way a grid is the same under every paint job. Those
 * live here.
 *
 * The second half derives the names components reach for (elevation, scrim,
 * inverse surface, tone tints) from skin tokens, so one skin change restyles
 * every overlay. Before this file existed, behaviors.css asked for
 * --ui-elevation-*, --ui-space-*, --ui-overlay-scrim and friends that no skin
 * defined, fell back to 26 hard-coded colours, and no skin could reach them.
 *
 * Everything sits in @layer platform-ui.tokens. A skin's :root is unlayered,
 * so a skin that does define one of these names always wins.
 */
@layer platform-ui.tokens {
    :root {
        /* Spacing — a 4px grid. */
        --ui-space-0: 0;
        --ui-space-px: 1px;
        --ui-space-0-5: 0.125rem;
        --ui-space-1: 0.25rem;
        --ui-space-1-5: 0.375rem;
        --ui-space-2: 0.5rem;
        --ui-space-2-5: 0.625rem;
        --ui-space-3: 0.75rem;
        --ui-space-3-5: 0.875rem;
        --ui-space-4: 1rem;
        --ui-space-5: 1.25rem;
        --ui-space-6: 1.5rem;
        --ui-space-8: 2rem;
        --ui-space-10: 2.5rem;
        --ui-space-12: 3rem;
        --ui-space-16: 4rem;
        --ui-space-20: 5rem;
        --ui-space-24: 6rem;

        /* Type scale — size / line-height pairs, tighter tracking as size grows. */
        --ui-text-xs: 0.75rem;
        --ui-text-xs-leading: 1rem;
        --ui-text-sm: 0.875rem;
        --ui-text-sm-leading: 1.25rem;
        --ui-text-base: 1rem;
        --ui-text-base-leading: 1.5rem;
        --ui-text-lg: 1.125rem;
        --ui-text-lg-leading: 1.75rem;
        --ui-text-xl: 1.25rem;
        --ui-text-xl-leading: 1.75rem;
        --ui-text-2xl: 1.5rem;
        --ui-text-2xl-leading: 2rem;
        --ui-text-3xl: 1.875rem;
        --ui-text-3xl-leading: 2.25rem;
        --ui-text-4xl: 2.25rem;
        --ui-text-4xl-leading: 2.5rem;
        --ui-text-5xl: 3rem;
        --ui-text-5xl-leading: 1.1;
        --ui-text-6xl: 3.75rem;
        --ui-text-6xl-leading: 1.05;

        --ui-tracking-tight: -0.015em;
        --ui-tracking-tighter: -0.025em;
        --ui-tracking-wide: 0.04em;

        --ui-font-weight-regular: 400;
        --ui-font-weight-medium: 500;
        --ui-font-weight-semibold: 600;
        --ui-font-weight-bold: 700;

        /* Controls — one height per size, shared by buttons, inputs, selects. */
        --ui-control-height-sm: 2rem;
        --ui-control-height-md: 2.375rem;
        --ui-control-height-lg: 2.75rem;
        --ui-control-padding-sm: 0.625rem;
        --ui-control-padding-md: 0.875rem;
        --ui-control-padding-lg: 1.125rem;

        /* Layout. */
        --ui-container-sm: 40rem;
        --ui-container-md: 48rem;
        --ui-container-lg: 64rem;
        --ui-container-xl: 80rem;
        --ui-container-max: var(--ui-container-lg);
        --ui-grid-min: 16rem;
        --ui-table-max-height: none;

        /* Focus. */
        --ui-focus-ring-width: 2px;
        --ui-focus-ring-offset: 2px;

        /* ---- Derived from the skin ---------------------------------------- */

        /* Elevation — named by intent, mapped onto the skin's shadow scale. */
        --ui-elevation-0: none;
        --ui-elevation-1: var(--ui-shadow-sm);
        --ui-elevation-2: var(--ui-shadow-md);
        --ui-elevation-3: var(--ui-shadow-lg);

        /* A hairline drawn as a shadow composes with elevation in one declaration. */
        --ui-hairline: 0 0 0 1px var(--ui-border-subtle);

        --ui-motion-duration-base: var(--ui-motion-duration-normal);
        --ui-text-body: var(--ui-text-primary);

        /* The surface a toast or tooltip sits on: the text colour, inverted. */
        --ui-surface-inverse: var(--ui-text-primary);
        --ui-text-on-inverse: var(--ui-surface-page);

        /* Dims the page behind a modal; dark in both modes, deeper in dark. */
        --ui-overlay-scrim: light-dark(rgb(15 17 26 / 0.45), rgb(0 0 0 / 0.62));

        /* Tone tints for soft variants: the tone over the raised surface. */
        --ui-tint-weak: 10%;
        --ui-tint-strong: 18%;
    }
}

/*
 * Density — one intent knob instead of a hundred overrides. Put
 * ui-density="compact" (dense admin tables, toolbars) or "comfortable" (touch,
 * marketing) on any container; every control, card and table inside rescales
 * because they size from these tokens, not from literals.
 */
@layer platform-ui.tokens {
    [ui-density="compact"] {
        --ui-control-height-sm: 1.75rem;
        --ui-control-height-md: 2rem;
        --ui-control-height-lg: 2.375rem;
        --ui-control-padding-sm: 0.5rem;
        --ui-control-padding-md: 0.625rem;
        --ui-control-padding-lg: 0.875rem;
    }
    [ui-density="comfortable"] {
        --ui-control-height-sm: 2.25rem;
        --ui-control-height-md: 2.75rem;
        --ui-control-height-lg: 3.25rem;
        --ui-control-padding-sm: 0.75rem;
        --ui-control-padding-md: 1rem;
        --ui-control-padding-lg: 1.375rem;
    }
}


@layer platform-ui.reset {
    *,
    *::before,
    *::after {
        box-sizing: border-box;
    }

    html {
        -webkit-text-size-adjust: 100%;
        text-size-adjust: 100%;
        tab-size: 4;
    }

    body {
        margin: 0;
        min-height: 100svh;
        line-height: 1.5;
        -webkit-font-smoothing: antialiased;
        text-rendering: optimizeLegibility;
    }

    h1, h2, h3, h4, h5, h6, p, figure, blockquote, dl, dd {
        margin: 0;
    }

    img, picture, video, canvas, svg {
        display: block;
        max-width: 100%;
    }

    input, button, textarea, select {
        font: inherit;
        color: inherit;
    }

    button {
        cursor: pointer;
        background: none;
        border: none;
        padding: 0;
    }

    :where([hidden]) {
        display: none !important;
    }

    :where(:focus-visible) {
        outline: 2px solid var(--ui-focus-ring, currentColor);
        outline-offset: 2px;
    }
}


@layer platform-ui.reset {
    :root {
        --ui-font-sans: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
        --ui-font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;

        font-family: var(--ui-font-sans);
        font-size: 16px;
        color: var(--ui-text-primary, inherit);
        background: var(--ui-surface-page, transparent);
    }

    code, kbd, samp, pre {
        font-family: var(--ui-font-mono);
        font-size: 0.9375em;
    }

    a {
        color: var(--ui-accent-brand, currentColor);
        text-decoration-skip-ink: auto;
    }

    /*
     * Headings get a scale. The reset zeroes their margins; until now nothing
     * sized them, so every page fell back to user-agent defaults and had no
     * hierarchy to speak of. :where() keeps the specificity at zero — any
     * project rule wins.
     */
    /* No colour here: a heading inherits from its container (a solid alert, a hero). */
    :where(h1, h2, h3, h4, h5, h6) {
        font-weight: var(--ui-font-weight-semibold);
        text-wrap: balance;
    }
    :where(h1) { font-size: var(--ui-text-4xl); line-height: var(--ui-text-4xl-leading); letter-spacing: var(--ui-tracking-tighter); }
    :where(h2) { font-size: var(--ui-text-3xl); line-height: var(--ui-text-3xl-leading); letter-spacing: var(--ui-tracking-tighter); }
    :where(h3) { font-size: var(--ui-text-2xl); line-height: var(--ui-text-2xl-leading); letter-spacing: var(--ui-tracking-tight); }
    :where(h4) { font-size: var(--ui-text-xl); line-height: var(--ui-text-xl-leading); letter-spacing: var(--ui-tracking-tight); }
    :where(h5) { font-size: var(--ui-text-lg); line-height: var(--ui-text-lg-leading); }
    :where(h6) { font-size: var(--ui-text-base); line-height: var(--ui-text-base-leading); }

    :where(p) { text-wrap: pretty; }

    /* Figures line up in tables and stats. */
    :where(table, [ui-component="stat"], [ui-component="table"]) { font-variant-numeric: tabular-nums; }
}


@layer platform-ui.grammar {
[sx-align="center"] { align-items: center; }
[sx-align="end"] { align-items: flex-end; }
[sx-align="start"] { align-items: flex-start; }
[sx-align="stretch"] { align-items: stretch; }
[sx-gap="0"] { gap: 0; }
[sx-gap="1"] { gap: var(--ui-space-1); }
[sx-gap="2"] { gap: var(--ui-space-2); }
[sx-gap="3"] { gap: var(--ui-space-3); }
[sx-gap="4"] { gap: var(--ui-space-4); }
[sx-gap="6"] { gap: var(--ui-space-6); }
[sx-gap="8"] { gap: var(--ui-space-8); }
[sx-justify="between"] { justify-content: space-between; }
[sx-justify="center"] { justify-content: center; }
[sx-justify="end"] { justify-content: flex-end; }
[sx-justify="start"] { justify-content: flex-start; }
[sx-layout="cluster"] { display: flex; flex-direction: row; flex-wrap: wrap; align-items: center; }
[sx-layout="container"] { display: block; width: 100%; max-width: var(--ui-container-max); margin-inline: auto; padding-inline: var(--ui-space-4); }
[sx-layout="frame"] { display: block; }
[sx-layout="grid"] { display: grid; grid-template-columns: repeat(auto-fit, minmax(min(var(--grid-min, var(--ui-grid-min, 16rem)), 100%), 1fr)); }
[sx-layout="stack"] { display: flex; flex-direction: column; }
[sx-padding="0"] { padding: 0; }
[sx-padding="1"] { padding: var(--ui-space-1); }
[sx-padding="2"] { padding: var(--ui-space-2); }
[sx-padding="3"] { padding: var(--ui-space-3); }
[sx-padding="4"] { padding: var(--ui-space-4); }
[sx-padding="6"] { padding: var(--ui-space-6); }
[sx-padding="8"] { padding: var(--ui-space-8); }
[sx-radius="lg"] { border-radius: var(--ui-radius-lg, 0.75rem); }
[sx-radius="md"] { border-radius: var(--ui-radius-md, 0.5rem); }
[sx-radius="none"] { border-radius: var(--ui-radius-none, 0); }
[sx-radius="pill"] { border-radius: var(--ui-radius-pill, 9999px); }
[sx-radius="sm"] { border-radius: var(--ui-radius-sm, 0.25rem); }
[sx-surface="flat"] { background: var(--ui-surface-page); color: var(--ui-text-primary); }
[sx-surface="panel"] { background: var(--ui-surface-panel); color: var(--ui-text-primary); border: 1px solid var(--ui-border-subtle); }
[sx-surface="raised"] { background: var(--ui-surface-raised); color: var(--ui-text-primary); border: 1px solid var(--ui-border-subtle); box-shadow: var(--ui-shadow-sm, 0 1px 3px rgba(0, 0, 0, 0.06)); }
[sx-tone="brand"] { color: var(--ui-accent-brand); }
[sx-tone="danger"] { color: var(--ui-state-danger); }
[sx-tone="neutral"] { color: var(--ui-text-muted); }
[sx-tone="success"] { color: var(--ui-state-success); }
[sx-tone="warning"] { color: var(--ui-state-warning); }
[ui-text="body"] { font-size: 0.9375rem; line-height: 1.5; color: var(--ui-text-primary); }
[ui-text="caption"] { font-size: var(--ui-text-xs); line-height: var(--ui-text-xs-leading); color: var(--ui-text-muted); }
[ui-text="display"] { font-size: clamp(var(--ui-text-4xl), 5vw, var(--ui-text-6xl)); line-height: var(--ui-text-6xl-leading); font-weight: var(--ui-font-weight-bold); letter-spacing: var(--ui-tracking-tighter); color: var(--ui-text-primary); text-wrap: balance; }
[ui-text="heading"] { font-size: var(--ui-text-2xl); line-height: var(--ui-text-2xl-leading); font-weight: var(--ui-font-weight-semibold); letter-spacing: var(--ui-tracking-tight); color: var(--ui-text-primary); text-wrap: balance; }
[ui-text="label"] { font-size: 0.8125rem; line-height: 1.4; font-weight: 500; color: var(--ui-text-primary); }
[ui-text="lead"] { font-size: var(--ui-text-lg); line-height: var(--ui-text-lg-leading); color: var(--ui-text-muted); text-wrap: pretty; }
[ui-text="muted"] { font-size: 0.9375rem; line-height: 1.5; color: var(--ui-text-muted); }
[ui-text="overline"] { font-size: var(--ui-text-xs); line-height: var(--ui-text-xs-leading); font-weight: var(--ui-font-weight-semibold); letter-spacing: var(--ui-tracking-wide); text-transform: uppercase; color: var(--ui-text-muted); }
[ui-text="title"] { font-size: var(--ui-text-xl); line-height: 1.3; font-weight: var(--ui-font-weight-semibold); color: var(--ui-text-primary); letter-spacing: var(--ui-tracking-tight); }
}

@layer platform-ui.primitives {
    /*
     * Tone colours the whole alert lightly (tinted surface, tinted border,
     * coloured icon); the body text stays at full contrast. Variants:
     * soft (default), outline, solid.
     */
    [ui="alert"] {
        --_tone: var(--ui-state-info);
        --_on-tone: var(--ui-text-on-info);

        display: flex;
        align-items: flex-start;
        gap: var(--ui-space-3);
        padding: var(--ui-space-3) var(--ui-space-4);
        border: 1px solid color-mix(in oklab, var(--_tone) 28%, var(--ui-border-subtle));
        border-radius: var(--ui-radius-lg, 0.75rem);
        background: color-mix(in oklab, var(--_tone) 7%, var(--ui-surface-raised));
        color: var(--ui-text-primary);
        font-size: var(--ui-text-sm);
        line-height: var(--ui-text-sm-leading);
    }

    [ui="alert"][ui-tone="neutral"] { --_tone: var(--ui-text-muted); --_on-tone: var(--ui-surface-page); }
    [ui="alert"][ui-tone="info"]    { --_tone: var(--ui-state-info);    --_on-tone: var(--ui-text-on-info); }
    [ui="alert"][ui-tone="success"] { --_tone: var(--ui-state-success); --_on-tone: var(--ui-text-on-success); }
    [ui="alert"][ui-tone="warning"] { --_tone: var(--ui-state-warning); --_on-tone: var(--ui-text-on-warning); }
    [ui="alert"][ui-tone="danger"]  { --_tone: var(--ui-state-danger);  --_on-tone: var(--ui-text-on-danger); }

    [ui="alert"] > .sx-icon {
        flex: none;
        width: 1.25rem;
        height: 1.25rem;
        color: var(--_tone);
    }

    [ui="alert"] > [data-alert-body] {
        min-width: 0;
        flex: 1;
        color: color-mix(in oklab, var(--ui-text-primary) 85%, var(--_tone));
    }
    [ui="alert"] [data-alert-title] {
        font-weight: var(--ui-font-weight-semibold);
        color: var(--ui-text-primary);
        margin-bottom: var(--ui-space-0-5);
    }

    [ui="alert"][ui-variant="outline"] { background: var(--ui-surface-raised); }
    [ui="alert"][ui-variant="solid"] {
        background: var(--_tone);
        border-color: transparent;
        color: var(--_on-tone);
    }
    [ui="alert"][ui-variant="solid"] > .sx-icon,
    [ui="alert"][ui-variant="solid"] > [data-alert-body],
    [ui="alert"][ui-variant="solid"] [data-alert-title] { color: inherit; }
}


@layer platform-ui.primitives {
    [ui="avatar"] {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        width: var(--sx-avatar-size, 2.5rem);
        height: var(--sx-avatar-size, 2.5rem);
        border-radius: var(--ui-radius-pill, 9999px);
        background: color-mix(in oklab, var(--ui-accent-brand) 14%, var(--ui-surface-raised));
        color: color-mix(in oklab, var(--ui-accent-brand) 80%, var(--ui-text-primary));
        box-shadow: 0 0 0 1px color-mix(in oklab, var(--ui-accent-brand) 18%, transparent);
        font-size: calc(var(--sx-avatar-size, 2.5rem) * 0.4);
        font-weight: var(--ui-font-weight-semibold);
        letter-spacing: var(--ui-tracking-tight);
        line-height: 1;
        overflow: hidden;
        user-select: none;
        flex-shrink: 0;
        vertical-align: middle;
    }

    [ui="avatar"] img {
        width: 100%;
        height: 100%;
        object-fit: cover;
        display: block;
    }

    [ui="avatar"][ui-size="sm"] { --sx-avatar-size: 1.75rem; }
    [ui="avatar"][ui-size="lg"] { --sx-avatar-size: 3.5rem; }
    [ui="avatar"][ui-size="xl"] { --sx-avatar-size: 5rem; }
}


@layer platform-ui.primitives {
    /*
     * Same two axes as the button: a tone names a colour, a variant decides how
     * it is used. Default is soft — a status label should inform, not shout.
     * A badge with no tone is neutral.
     */
    [ui="badge"] {
        --_tone: var(--ui-text-muted);
        --_on-tone: var(--ui-surface-page);

        display: inline-flex;
        align-items: center;
        gap: var(--ui-space-1);
        min-height: 1.375rem;
        padding: 0 var(--ui-space-2);
        border: 1px solid transparent;
        border-radius: var(--ui-radius-pill, 9999px);
        font-size: var(--ui-text-xs);
        font-weight: var(--ui-font-weight-medium);
        line-height: 1;
        white-space: nowrap;
        font-variant-numeric: tabular-nums;
    }
    [ui="badge"][ui-size="sm"] { min-height: 1.125rem; padding: 0 var(--ui-space-1-5); font-size: 0.6875rem; }

    [ui="badge"][ui-tone="neutral"] { --_tone: var(--ui-text-muted); --_on-tone: var(--ui-surface-page); }
    [ui="badge"][ui-tone="brand"]   { --_tone: var(--ui-accent-brand); --_on-tone: var(--ui-text-on-accent); }
    [ui="badge"][ui-tone="info"]    { --_tone: var(--ui-state-info);    --_on-tone: var(--ui-text-on-info); }
    [ui="badge"][ui-tone="success"] { --_tone: var(--ui-state-success); --_on-tone: var(--ui-text-on-success); }
    [ui="badge"][ui-tone="warning"] { --_tone: var(--ui-state-warning); --_on-tone: var(--ui-text-on-warning); }
    [ui="badge"][ui-tone="danger"]  { --_tone: var(--ui-state-danger);  --_on-tone: var(--ui-text-on-danger); }

    /* Soft and outline text mix the tone toward the text colour: an amber
       warning at 85% read 3.06:1 on its own tint (axe, light skin), below AA's
       4.5:1 for 12px text. 62% keeps the hue and clears AA in both modes. */
    [ui="badge"]:where(:not([ui-variant]), [ui-variant="soft"]) {
        background: color-mix(in oklab, var(--_tone) 13%, var(--ui-surface-raised));
        color: color-mix(in oklab, var(--_tone) 62%, var(--ui-text-primary));
        border-color: color-mix(in oklab, var(--_tone) 22%, transparent);
    }
    [ui="badge"][ui-variant="solid"] {
        background: var(--_tone);
        color: var(--_on-tone);
    }
    [ui="badge"][ui-variant="outline"] {
        background: transparent;
        color: color-mix(in oklab, var(--_tone) 62%, var(--ui-text-primary));
        border-color: color-mix(in oklab, var(--_tone) 50%, transparent);
    }

    /* A leading dot: <span ui="badge" ui-dot>Live</span>. */
    [ui="badge"][ui-dot]::before {
        content: "";
        width: 0.375rem;
        height: 0.375rem;
        border-radius: 50%;
        background: var(--_tone);
    }
    [ui="badge"][ui-variant="solid"][ui-dot]::before { background: currentColor; }
    [ui="badge"] > .sx-icon { width: 0.875em; height: 0.875em; }
}


@layer platform-ui.primitives {
    /*
     * Tone and variant are independent axes. A tone only names a colour
     * (--_tone, and the text that sits on it); a variant only decides how that
     * colour is used. Every pair works, including a tone with no variant.
     *
     * Before this split the colour rules were written per pair and required
     * ui-variant="solid" to be spelled out, so ui-tone="danger" on its own
     * rendered the brand colour.
     */
    [ui="button"] {
        --_tone: var(--ui-accent-brand);
        --_on-tone: var(--ui-text-on-accent);
        --_height: var(--ui-control-height-md);
        --_pad: var(--ui-control-padding-md);

        position: relative;
        display: inline-flex;
        align-items: center;
        justify-content: center;
        gap: var(--ui-space-2);
        min-height: var(--_height);
        padding: 0 var(--_pad);
        border: 1px solid transparent;
        border-radius: var(--ui-radius-md, 0.5rem);
        font: inherit;
        font-size: var(--ui-text-sm);
        font-weight: var(--ui-font-weight-medium);
        line-height: 1;
        cursor: pointer;
        white-space: nowrap;
        user-select: none;
        text-decoration: none;
        transition:
            background-color var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease),
            border-color     var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease),
            color            var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease),
            box-shadow       var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease),
            transform        var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease);
    }

    /* Sizes */
    [ui="button"][ui-size="sm"] {
        --_height: var(--ui-control-height-sm);
        --_pad: var(--ui-control-padding-sm);
        font-size: var(--ui-text-xs);
        border-radius: var(--ui-radius-sm, 0.375rem);
    }
    [ui="button"][ui-size="lg"] {
        --_height: var(--ui-control-height-lg);
        --_pad: var(--ui-control-padding-lg);
        font-size: var(--ui-text-base);
    }

    /* Tones — colour only */
    [ui="button"][ui-tone="neutral"] { --_tone: var(--ui-text-primary); --_on-tone: var(--ui-surface-page); }
    [ui="button"][ui-tone="success"] { --_tone: var(--ui-state-success); --_on-tone: var(--ui-text-on-success); }
    [ui="button"][ui-tone="warning"] { --_tone: var(--ui-state-warning); --_on-tone: var(--ui-text-on-warning); }
    [ui="button"][ui-tone="danger"]  { --_tone: var(--ui-state-danger);  --_on-tone: var(--ui-text-on-danger); }
    [ui="button"][ui-tone="info"]    { --_tone: var(--ui-state-info);    --_on-tone: var(--ui-text-on-info); }

    /* Variants — how the tone is used */
    [ui="button"]:where(:not([ui-variant]), [ui-variant="solid"]) {
        background: var(--_tone);
        color: var(--_on-tone);
        box-shadow:
            inset 0 1px 0 rgb(255 255 255 / 0.14),
            0 1px 2px color-mix(in oklab, var(--_tone) 35%, transparent);
    }
    [ui="button"]:where(:not([ui-variant]), [ui-variant="solid"]):hover:not(:disabled, [aria-disabled="true"]) {
        background: color-mix(in oklab, var(--_tone) 88%, black);
    }

    /* Soft: the tone tinted onto the surface. Without a tone it is a quiet neutral button. */
    [ui="button"][ui-variant="soft"] {
        background: color-mix(in oklab, var(--_tone) var(--ui-tint-weak), var(--ui-surface-raised));
        color: color-mix(in oklab, var(--_tone) 82%, var(--ui-text-primary));
        border-color: color-mix(in oklab, var(--_tone) var(--ui-tint-strong), transparent);
    }
    [ui="button"][ui-variant="soft"]:hover:not(:disabled, [aria-disabled="true"]) {
        background: color-mix(in oklab, var(--_tone) var(--ui-tint-strong), var(--ui-surface-raised));
    }
    [ui="button"][ui-variant="soft"]:where(:not([ui-tone])) {
        background: var(--ui-surface-raised);
        color: var(--ui-text-primary);
        border-color: var(--ui-border-subtle);
        box-shadow: var(--ui-shadow-xs);
    }
    [ui="button"][ui-variant="soft"]:where(:not([ui-tone])):hover:not(:disabled, [aria-disabled="true"]) {
        background: var(--ui-surface-panel);
        border-color: var(--ui-border-strong);
    }

    /* Outline: a border in the tone, no fill. */
    [ui="button"][ui-variant="outline"] {
        background: transparent;
        color: var(--_tone);
        border-color: color-mix(in oklab, var(--_tone) 55%, transparent);
    }
    [ui="button"][ui-variant="outline"]:hover:not(:disabled, [aria-disabled="true"]) {
        background: color-mix(in oklab, var(--_tone) var(--ui-tint-weak), transparent);
    }

    /* Ghost: text only until hovered. Without a tone it uses the body text colour. */
    [ui="button"][ui-variant="ghost"] {
        background: transparent;
        color: var(--_tone);
    }
    [ui="button"][ui-variant="ghost"]:where(:not([ui-tone])) { color: var(--ui-text-primary); }
    [ui="button"][ui-variant="ghost"]:hover:not(:disabled, [aria-disabled="true"]) {
        background: color-mix(in oklab, var(--_tone) var(--ui-tint-weak), transparent);
    }
    [ui="button"][ui-variant="ghost"]:where(:not([ui-tone])):hover:not(:disabled, [aria-disabled="true"]) {
        background: var(--ui-surface-panel);
    }

    /* Link: an inline action that reads as text. */
    [ui="button"][ui-variant="link"] {
        min-height: auto;
        padding: 0;
        background: transparent;
        color: var(--_tone);
        text-decoration: underline;
        text-decoration-color: color-mix(in oklab, var(--_tone) 40%, transparent);
        text-underline-offset: 0.2em;
    }

    /* States */
    [ui="button"]:focus-visible {
        outline: var(--ui-focus-ring-width) solid var(--ui-focus-ring);
        outline-offset: var(--ui-focus-ring-offset);
    }
    [ui="button"]:active:not(:disabled, [aria-disabled="true"]) { transform: translateY(1px) scale(0.99); }
    [ui="button"]:is(:disabled, [aria-disabled="true"]) {
        opacity: 0.5;
        cursor: not-allowed;
        pointer-events: none;
        box-shadow: none;
    }
    /* Pressed outranks every variant fallback above (they are :where()-flattened). */
    [ui="button"][aria-pressed="true"][aria-pressed] {
        background: color-mix(in oklab, var(--_tone) var(--ui-tint-strong), var(--ui-surface-raised));
        color: var(--_tone);
        border-color: color-mix(in oklab, var(--_tone) 40%, transparent);
    }

    /* Loading: keeps the width, hides the label, shows a ring. */
    [ui="button"][ui-state="loading"] {
        color: transparent !important;
        pointer-events: none;
    }
    [ui="button"]:is([ui-state="loading"], [data-loading])::after {
        content: "";
        position: absolute;
        inset: 0;
        margin: auto;
        width: 1em;
        height: 1em;
        border-radius: 50%;
        border: 2px solid var(--_on-tone);
        border-right-color: transparent;
        animation: ui-button-spin 0.7s linear infinite;
    }
    [ui="button"]:is([ui-variant="soft"], [ui-variant="outline"], [ui-variant="ghost"], [ui-variant="link"]):is([ui-state="loading"], [data-loading])::after {
        border-color: var(--_tone);
        border-right-color: transparent;
    }

    /* An action in flight from this button (the event runtime sets
       data-loading): the same ring, after a short grace period so a fast
       answer never flickers. */
    [ui="button"][data-loading] {
        pointer-events: none;
        animation: ui-button-busy 0s linear 150ms forwards;
    }
    [ui="button"][data-loading]::after {
        opacity: 0;
        animation: ui-button-spin 0.7s linear infinite, ui-button-appear 0s linear 150ms forwards;
    }
    @keyframes ui-button-busy { to { color: transparent; } }
    @keyframes ui-button-appear { to { opacity: 1; } }

    /* Icons inside buttons size with the text. */
    [ui="button"] > .sx-icon { width: 1.15em; height: 1.15em; flex: none; }
    [ui="button"][ui-shape="square"] { padding: 0; width: var(--_height); }

    @keyframes ui-button-spin { to { transform: rotate(1turn); } }

    @media (prefers-reduced-motion: reduce) {
        [ui="button"] { transition: none; }
        [ui="button"][ui-state="loading"]::after { animation-duration: 1.6s; }
    }
}


@layer platform-ui.primitives {
    /* checkbox · radio · switch — a <label> root around the native control,
       drawn from tokens (appearance: none), focus / invalid / disabled alike. */
    :is([ui="checkbox"], [ui="radio"], [ui="switch"]) {
        display: inline-flex;
        align-items: center;
        gap: var(--ui-space-2);
        font-size: var(--ui-text-sm);
        line-height: var(--ui-text-sm-leading);
        color: var(--ui-text-primary);
        cursor: pointer;
    }
    :is([ui="checkbox"], [ui="radio"], [ui="switch"]) > input {
        appearance: none;
        flex: none;
        margin: 0;
        display: inline-grid;
        place-content: center;
        background: var(--ui-surface-raised);
        border: 1px solid var(--ui-border-strong);
        cursor: inherit;
        transition:
            background-color var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease),
            border-color var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease);
    }
    :is([ui="checkbox"], [ui="radio"], [ui="switch"]) > input:focus-visible {
        outline: none;
        box-shadow: 0 0 0 3px color-mix(in oklab, var(--ui-focus-ring) 30%, transparent);
    }
    :is([ui="checkbox"], [ui="radio"], [ui="switch"]) > input[aria-invalid="true"] { border-color: var(--ui-state-danger); }
    :is([ui="checkbox"], [ui="radio"], [ui="switch"]):has(> input:disabled) { color: var(--ui-text-muted); cursor: not-allowed; }
    :is([ui="checkbox"], [ui="radio"], [ui="switch"]) > input:disabled { opacity: 0.55; }

    /* checkbox: a rounded square, a check mark drawn by clip-path */
    [ui="checkbox"] > input { width: 1.125rem; height: 1.125rem; border-radius: var(--ui-radius-sm, 0.25rem); }
    [ui="checkbox"] > input::before {
        content: "";
        width: 0.625rem;
        height: 0.625rem;
        background: var(--ui-text-on-accent);
        clip-path: polygon(14% 44%, 0 65%, 50% 100%, 100% 16%, 80% 0%, 43% 62%);
        scale: 0;
        transition: scale var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease);
    }
    [ui="checkbox"] > input:checked { background: var(--ui-accent-brand); border-color: var(--ui-accent-brand); }
    [ui="checkbox"] > input:checked::before { scale: 1; }

    /* radio: a circle with a dot */
    [ui="radio"] > input { width: 1.125rem; height: 1.125rem; border-radius: 50%; }
    [ui="radio"] > input::before {
        content: "";
        width: 0.5rem;
        height: 0.5rem;
        border-radius: 50%;
        background: var(--ui-accent-brand);
        scale: 0;
        transition: scale var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease);
    }
    [ui="radio"] > input:checked { border-color: var(--ui-accent-brand); }
    [ui="radio"] > input:checked::before { scale: 1; }

    /* switch: a track with a thumb that slides */
    [ui="switch"] > input {
        width: 2.25rem;
        height: 1.25rem;
        border-radius: 999px;
        place-content: center start;
        padding: 0.125rem;
        background: var(--ui-surface-sunken);
    }
    [ui="switch"] > input::before {
        content: "";
        width: 0.875rem;
        height: 0.875rem;
        border-radius: 50%;
        background: var(--ui-surface-raised);
        box-shadow: var(--ui-shadow-xs);
        transition: translate var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease);
    }
    [ui="switch"] > input:checked { background: var(--ui-accent-brand); border-color: var(--ui-accent-brand); }
    [ui="switch"] > input:checked::before { translate: 1rem 0; }

    @media (prefers-reduced-motion: reduce) {
        :is([ui="checkbox"], [ui="radio"], [ui="switch"]) > input,
        :is([ui="checkbox"], [ui="radio"], [ui="switch"]) > input::before { transition: none; }
    }
}


@layer platform-ui.primitives {
    /* Side by side where the container has room, stacked where it has not —
       a container query, so it adapts to the column it sits in, not the window. */
    [ui="description-list"] { container-type: inline-size; margin: 0; display: grid; gap: 0; }
    [ui="description-list"] > div {
        display: grid;
        gap: var(--ui-space-1);
        padding: var(--ui-space-2-5) 0;
        border-top: 1px solid var(--ui-border-subtle);
    }
    [ui="description-list"] > div:first-child { border-top: 0; }
    [ui="description-list"] dt { font-size: var(--ui-text-sm); color: var(--ui-text-muted); font-weight: var(--ui-font-weight-medium); }
    [ui="description-list"] dd { margin: 0; font-size: var(--ui-text-sm); color: var(--ui-text-primary); }
    @container (min-width: 28rem) {
        [ui="description-list"][ui-layout="inline"] > div { grid-template-columns: minmax(8rem, 1fr) 2fr; gap: var(--ui-space-4); }
    }
}


@layer platform-ui.primitives {
    hr[ui="divider"] { border: 0; border-top: 1px solid var(--ui-border-subtle); margin: var(--ui-space-3) 0; width: 100%; }
    [ui="divider"][aria-orientation="vertical"] { align-self: stretch; width: 0; min-height: 1em; border-left: 1px solid var(--ui-border-subtle); margin: 0 var(--ui-space-2); }
    [ui="divider"][ui-divider-label] {
        display: flex;
        align-items: center;
        gap: var(--ui-space-3);
        margin: var(--ui-space-3) 0;
        color: var(--ui-text-muted);
        font-size: var(--ui-text-xs);
        text-transform: uppercase;
        letter-spacing: 0.06em;
    }
    [ui="divider"][ui-divider-label]::before,
    [ui="divider"][ui-divider-label]::after { content: ""; flex: 1; border-top: 1px solid var(--ui-border-subtle); }
}


@layer platform-ui.primitives {
    [ui="field-shell"] {
        display: block;
    }

    [ui="field-shell"][ui-size="sm"] [ui="label"] { font-size: var(--ui-text-xs); }
    [ui="field-shell"][ui-size="lg"] [ui="label"] { font-size: var(--ui-text-base); }
    [ui="field-shell"][ui-size="sm"] [ui="input"] { --_height: var(--ui-control-height-sm); font-size: var(--ui-text-xs); }
    [ui="field-shell"][ui-size="lg"] [ui="input"] { --_height: var(--ui-control-height-lg); font-size: var(--ui-text-base); }

    [ui="field-shell"][ui-state="invalid"] [ui="label"] { color: var(--ui-state-danger); }
    [ui="field-shell"][ui-state="invalid"] [ui="input"] { border-color: var(--ui-state-danger); }

    [ui="field-shell"] [ui="error-text"] {
        display: block;
        font-size: var(--ui-text-xs);
        color: var(--ui-state-danger);
        margin-top: var(--ui-space-1-5);
        line-height: 1.4;
    }

    [ui="field-shell"]:not([ui-state="invalid"]) [ui="error-text"] { display: none; }
}


@layer platform-ui.primitives {
    :is([ui="input"], [ui="textarea"], [ui="select"]) {
        --_height: var(--ui-control-height-md);

        display: block;
        width: 100%;
        min-height: var(--_height);
        font: inherit;
        font-size: var(--ui-text-sm);
        line-height: var(--ui-text-sm-leading);
        color: var(--ui-text-primary);
        background: var(--ui-surface-raised);
        border: 1px solid var(--ui-border-subtle);
        border-radius: var(--ui-radius-md, 0.5rem);
        padding: var(--ui-space-1-5) var(--ui-space-3);
        box-shadow: var(--ui-shadow-xs);
        transition:
            border-color var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease),
            box-shadow   var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease);
    }
    textarea[ui="input"], [ui="textarea"] { min-height: calc(var(--_height) * 2.5); resize: vertical; }

    :is([ui="input"], [ui="textarea"], [ui="select"])[ui-size="sm"] { --_height: var(--ui-control-height-sm); padding: var(--ui-space-1) var(--ui-space-2-5); font-size: var(--ui-text-xs); }
    :is([ui="input"], [ui="textarea"], [ui="select"])[ui-size="lg"] { --_height: var(--ui-control-height-lg); padding: var(--ui-space-2) var(--ui-space-3-5); font-size: var(--ui-text-base); }

    :is([ui="input"], [ui="textarea"], [ui="select"])::placeholder { color: var(--ui-text-muted); opacity: 0.8; }

    :is([ui="input"], [ui="textarea"], [ui="select"]):hover:not(:disabled, :focus) { border-color: var(--ui-border-strong); }

    :is([ui="input"], [ui="textarea"], [ui="select"]):focus,
    :is([ui="input"], [ui="textarea"], [ui="select"]):focus-visible {
        outline: none;
        border-color: var(--ui-focus-ring);
        box-shadow: 0 0 0 3px color-mix(in oklab, var(--ui-focus-ring) 22%, transparent);
    }

    :is([ui="input"], [ui="textarea"], [ui="select"])[ui-state="invalid"],
    :is([ui="input"], [ui="textarea"], [ui="select"])[aria-invalid="true"] { border-color: var(--ui-state-danger); }
    :is([ui="input"], [ui="textarea"], [ui="select"])[ui-state="invalid"]:focus,
    :is([ui="input"], [ui="textarea"], [ui="select"])[aria-invalid="true"]:focus {
        box-shadow: 0 0 0 3px color-mix(in oklab, var(--ui-state-danger) 22%, transparent);
    }

    :is([ui="input"], [ui="textarea"], [ui="select"]):disabled {
        background: var(--ui-surface-sunken);
        color: var(--ui-text-muted);
        box-shadow: none;
        cursor: not-allowed;
    }
    /* A select always matches :read-only (it is not a text control). */
    :is([ui="input"], [ui="textarea"]):read-only:not(:disabled) { background: var(--ui-surface-panel); }
}


@layer platform-ui.primitives {
    [ui="kbd"] { display: inline-flex; align-items: center; gap: 0.25rem; font-size: var(--ui-text-xs); color: var(--ui-text-muted); }
    [ui="kbd"] > kbd {
        display: inline-grid;
        place-items: center;
        min-width: 1.5rem;
        height: 1.375rem;
        padding: 0 0.375rem;
        font: inherit;
        font-family: var(--ui-font-mono, ui-monospace, monospace);
        color: var(--ui-text-primary);
        background: var(--ui-surface-raised);
        border: 1px solid var(--ui-border-subtle);
        border-bottom-width: 2px;
        border-radius: var(--ui-radius-sm, 0.25rem);
    }
}


@layer platform-ui.primitives {
    [ui="label"] {
        display: block;
        font-size: var(--ui-text-sm);
        font-weight: var(--ui-font-weight-medium);
        color: var(--ui-text-primary);
        margin-bottom: var(--ui-space-1-5);
        line-height: var(--ui-text-sm-leading);
    }

    [ui="label"][ui-size="sm"] { font-size: var(--ui-text-xs); margin-bottom: var(--ui-space-1); }
    [ui="label"][ui-size="lg"] { font-size: var(--ui-text-base); }

    /* <label ui="label" ui-required> appends a quiet marker. */
    [ui="label"][ui-required]::after { content: " *"; color: var(--ui-state-danger); }
}


@layer platform-ui.primitives {
    /* progress · meter — native elements, drawn from tokens. */
    :is([ui="progress"], [ui="meter"]) {
        --_tone: var(--ui-accent-brand);
        --_track: color-mix(in oklab, var(--ui-text-muted) 18%, var(--ui-surface-raised));
        --_height: 0.5rem;
        display: grid;
        gap: var(--ui-space-1);
        width: 100%;
    }
    [ui="progress"][ui-size="sm"] { --_height: 0.25rem; }
    [ui="progress"][ui-size="lg"] { --_height: 0.75rem; }
    [ui="progress"][ui-tone="neutral"] { --_tone: var(--ui-text-muted); }
    [ui="progress"][ui-tone="info"]    { --_tone: var(--ui-state-info); }
    [ui="progress"][ui-tone="success"] { --_tone: var(--ui-state-success); }
    [ui="progress"][ui-tone="warning"] { --_tone: var(--ui-state-warning); }
    [ui="progress"][ui-tone="danger"]  { --_tone: var(--ui-state-danger); }

    [ui-progress-caption] {
        display: flex;
        justify-content: space-between;
        gap: var(--ui-space-2);
        font-size: var(--ui-text-sm);
        color: var(--ui-text-primary);
    }
    [ui-progress-value] { color: var(--ui-text-muted); font-variant-numeric: tabular-nums; }

    :is([ui="progress"] > progress, [ui="meter"] > meter) {
        appearance: none;
        display: block;
        width: 100%;
        height: var(--_height);
        border: 0;
        border-radius: 999px;
        overflow: hidden;
        background: var(--_track);
    }
    [ui="progress"] > progress::-webkit-progress-bar { background: var(--_track); border-radius: 999px; }
    [ui="progress"] > progress::-webkit-progress-value {
        background: var(--_tone);
        border-radius: 999px;
        transition: inline-size var(--ui-motion-duration-base, 200ms) var(--ui-motion-easing-standard, ease);
    }
    [ui="progress"] > progress::-moz-progress-bar { background: var(--_tone); border-radius: 999px; }

    /* Indeterminate: a band sweeping across the track. */
    [ui="progress"] > progress:indeterminate {
        background:
            linear-gradient(90deg, transparent, var(--_tone), transparent) no-repeat,
            var(--_track);
        background-size: 40% 100%, auto;
        animation: ui-progress-sweep 1.2s var(--ui-motion-easing-standard, ease-in-out) infinite;
    }
    [ui="progress"] > progress:indeterminate::-webkit-progress-bar { background: transparent; }
    [ui="progress"] > progress:indeterminate::-moz-progress-bar { background: transparent; }
    @keyframes ui-progress-sweep {
        from { background-position: -40% 0, 0 0; }
        to   { background-position: 140% 0, 0 0; }
    }

    /* meter: the browser picks the segment; we colour it. */
    [ui="meter"] > meter::-webkit-meter-bar { background: var(--_track); border: 0; border-radius: 999px; height: var(--_height); }
    [ui="meter"] > meter::-webkit-meter-optimum-value { background: var(--ui-state-success); border-radius: 999px; }
    [ui="meter"] > meter::-webkit-meter-suboptimum-value { background: var(--ui-state-warning); border-radius: 999px; }
    [ui="meter"] > meter::-webkit-meter-even-less-good-value { background: var(--ui-state-danger); border-radius: 999px; }
    [ui="meter"] > meter:-moz-meter-optimum::-moz-meter-bar { background: var(--ui-state-success); }
    [ui="meter"] > meter:-moz-meter-sub-optimum::-moz-meter-bar { background: var(--ui-state-warning); }
    [ui="meter"] > meter:-moz-meter-sub-sub-optimum::-moz-meter-bar { background: var(--ui-state-danger); }

    @media (prefers-reduced-motion: reduce) {
        [ui="progress"] > progress:indeterminate { animation: none; background-position: 50% 0, 0 0; }
        [ui="progress"] > progress::-webkit-progress-value { transition: none; }
    }
}


@layer platform-ui.primitives {
    /* A radio group drawn as one button bar; the radios stay real (keyboard,
       form value), only visually hidden. */
    [ui="segmented"] {
        display: inline-flex;
        gap: 0.125rem;
        margin: 0;
        padding: 0.1875rem;
        border: 1px solid var(--ui-border-subtle);
        border-radius: var(--ui-radius-md, 0.5rem);
        background: var(--ui-surface-sunken);
        min-inline-size: 0;
        /* Its own width, even as a child of a stretching stack. */
        inline-size: fit-content;
        max-inline-size: 100%;
        align-self: flex-start;
    }
    [ui="segmented"] > label {
        position: relative;
        display: inline-flex;
        align-items: center;
        min-height: calc(var(--ui-control-height-md) - 0.5rem);
        padding: 0 var(--ui-space-3);
        border-radius: calc(var(--ui-radius-md, 0.5rem) - 0.1875rem);
        font-size: var(--ui-text-sm);
        color: var(--ui-text-muted);
        cursor: pointer;
        transition: background-color var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease), color var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease);
    }
    [ui="segmented"][ui-size="sm"] > label { min-height: calc(var(--ui-control-height-sm) - 0.5rem); padding: 0 var(--ui-space-2); font-size: var(--ui-text-xs); }
    /* The label takes the click (it activates its radio); the input keeps focus and keys. */
    [ui="segmented"] > label > input { position: absolute; opacity: 0; inset: 0; margin: 0; pointer-events: none; }
    [ui="segmented"] > label:hover { color: var(--ui-text-primary); }
    [ui="segmented"] > label:has(> input:checked) { background: var(--ui-surface-raised); color: var(--ui-text-primary); box-shadow: var(--ui-shadow-xs); }
    [ui="segmented"] > label:has(> input:focus-visible) { box-shadow: 0 0 0 2px var(--ui-focus-ring); }
    [ui="segmented"][aria-invalid="true"] { border-color: var(--ui-state-danger); }
    [ui="segmented"] > label > svg { flex: none; }
    [ui="segmented"] > label > svg + span { margin-inline-start: var(--ui-space-1-5); }
    /* Icons only: the label text stays for assistive technology. */
    [ui="segmented"][ui-icon-only] > label { padding: 0 var(--ui-space-2); }
    [ui="segmented"][ui-icon-only] > label > span {
        position: absolute;
        width: 1px;
        height: 1px;
        overflow: hidden;
        clip-path: inset(50%);
        white-space: nowrap;
    }
}


@layer platform-ui.primitives {
    /* The shared control look lives in input.css; here only the select's own. */
    [ui="select"]:not([multiple]) {
        appearance: none;
        padding-inline-end: calc(var(--ui-space-3) + 1.25rem);
        /* A chevron from two gradients: inherits the token colour, no image. */
        background-image:
            linear-gradient(45deg, transparent 50%, var(--ui-text-muted) 50%),
            linear-gradient(135deg, var(--ui-text-muted) 50%, transparent 50%);
        background-position:
            calc(100% - var(--ui-space-3) - 0.3125rem) 50%,
            calc(100% - var(--ui-space-3)) 50%;
        background-size: 0.3125rem 0.3125rem, 0.3125rem 0.3125rem;
        background-repeat: no-repeat;
        cursor: pointer;
    }
    [ui="select"][multiple] { padding: var(--ui-space-1); }
    [ui="select"][multiple] option { padding: var(--ui-space-1) var(--ui-space-2); border-radius: var(--ui-radius-sm, 0.25rem); }

    /* Customizable select where the browser has it: the open list is styled
       from tokens too, and the native picker icon replaces the gradient. */
    @supports (appearance: base-select) {
        [ui="select"]:not([multiple]),
        [ui="select"]:not([multiple])::picker(select) { appearance: base-select; }
        [ui="select"]:not([multiple]) {
            display: flex;
            align-items: center;
            justify-content: space-between;
            gap: var(--ui-space-2);
            background-image: none;
            padding-inline-end: var(--ui-space-3);
        }
        [ui="select"]::picker-icon { color: var(--ui-text-muted); transition: rotate var(--ui-motion-duration-fast, 120ms) var(--ui-motion-easing-standard, ease); }
        [ui="select"]:open::picker-icon { rotate: 180deg; }
        [ui="select"]::picker(select) {
            margin-block: var(--ui-space-1);
            padding: var(--ui-space-1);
            background: var(--ui-surface-raised);
            color: var(--ui-text-primary);
            border: 1px solid var(--ui-border-subtle);
            border-radius: var(--ui-radius-md, 0.5rem);
            box-shadow: var(--ui-shadow-md, var(--ui-shadow-xs));
        }
        [ui="select"]:not([multiple]) option {
            padding: var(--ui-space-1-5) var(--ui-space-2-5);
            border-radius: var(--ui-radius-sm, 0.25rem);
        }
        [ui="select"]:not([multiple]) option:is(:hover, :focus-visible) { background: var(--ui-surface-sunken); outline: none; }
        [ui="select"]:not([multiple]) option:checked { font-weight: 600; }
        [ui="select"] option::checkmark { color: var(--ui-accent-brand); }
    }
}


@layer platform-ui.primitives {
    [ui="skeleton"] {
        --_base: color-mix(in oklab, var(--ui-text-muted) 14%, var(--ui-surface-raised));
        --_shine: color-mix(in oklab, var(--ui-text-muted) 6%, var(--ui-surface-raised));
        display: block;
        width: var(--_w, 100%);
    }
    :is([ui="skeleton"]:not([ui-shape="text"]), [ui-skeleton-line]) {
        background: linear-gradient(90deg, var(--_base) 25%, var(--_shine) 50%, var(--_base) 75%) 0 0 / 300% 100%;
        animation: ui-skeleton-shimmer 1.6s linear infinite;
    }
    [ui="skeleton"][ui-shape="text"] { display: grid; gap: var(--ui-space-2); }
    [ui-skeleton-line] { display: block; height: var(--_h, 0.75rem); border-radius: var(--ui-radius-sm, 0.25rem); }
    [ui-skeleton-line]:last-child:not(:first-child) { width: 60%; }
    [ui="skeleton"][ui-shape="circle"] { width: var(--_w, 2.5rem); aspect-ratio: 1; border-radius: 50%; }
    [ui="skeleton"][ui-shape="rect"] { height: var(--_h, 6rem); border-radius: var(--ui-radius-md, 0.5rem); }
    @keyframes ui-skeleton-shimmer { from { background-position: 100% 0; } to { background-position: 0 0; } }
    @media (prefers-reduced-motion: reduce) {
        :is([ui="skeleton"]:not([ui-shape="text"]), [ui-skeleton-line]) { animation: none; background: var(--_base); }
    }
}


@layer platform-ui.primitives {
    [ui="spinner"] {
        display: inline-block;
        width: var(--sx-spinner-size, 1.25rem);
        height: var(--sx-spinner-size, 1.25rem);
        border: var(--sx-spinner-weight, 2px) solid var(--ui-border-subtle);
        border-top-color: var(--ui-accent-brand);
        border-radius: var(--ui-radius-pill, 9999px);
        vertical-align: middle;
        flex-shrink: 0;
        animation: sx-spinner-spin var(--ui-motion-duration-slow, 720ms) linear infinite;
    }

    [ui="spinner"][ui-size="sm"] { --sx-spinner-size: 0.875rem; --sx-spinner-weight: 2px; }
    [ui="spinner"][ui-size="lg"] { --sx-spinner-size: 2rem; --sx-spinner-weight: 3px; }

    [ui="spinner"][ui-tone="neutral"] { border-top-color: var(--ui-text-muted); }

    @media (prefers-reduced-motion: reduce) {
        [ui="spinner"] { animation-duration: 1600ms; }
    }

    @keyframes sx-spinner-spin {
        to { transform: rotate(360deg); }
    }
}


@layer platform-ui.primitives {
    [ui="surface"] {
        display: block;
        background: var(--ui-surface-panel);
        color: var(--ui-text-primary);
        border: 1px solid var(--ui-border-subtle);
        border-radius: var(--ui-radius-lg, 0.75rem);
        padding: var(--ui-space-4);
    }
}


@layer platform-ui.primitives {
    /* The badge's tone mechanics, as a chip that can be removed. */
    [ui="tag"] {
        --_tone: var(--ui-text-muted);
        display: inline-flex;
        align-items: center;
        gap: var(--ui-space-1);
        min-height: 1.625rem;
        padding: 0 var(--ui-space-2-5);
        border-radius: var(--ui-radius-md, 0.5rem);
        font-size: var(--ui-text-xs);
        font-weight: var(--ui-font-weight-medium);
        line-height: 1;
        white-space: nowrap;
        background: color-mix(in oklab, var(--_tone) 12%, var(--ui-surface-raised));
        color: color-mix(in oklab, var(--_tone) 80%, var(--ui-text-primary));
        border: 1px solid color-mix(in oklab, var(--_tone) 22%, transparent);
    }
    [ui="tag"][ui-tone="brand"]   { --_tone: var(--ui-accent-brand); }
    [ui="tag"][ui-tone="info"]    { --_tone: var(--ui-state-info); }
    [ui="tag"][ui-tone="success"] { --_tone: var(--ui-state-success); }
    [ui="tag"][ui-tone="warning"] { --_tone: var(--ui-state-warning); }
    [ui="tag"][ui-tone="danger"]  { --_tone: var(--ui-state-danger); }
    [ui="tag"] > [ui-removable-trigger] {
        display: inline-grid;
        place-items: center;
        width: 1.125rem;
        height: 1.125rem;
        margin-inline-end: calc(var(--ui-space-1) * -1);
        padding: 0;
        border: 0;
        border-radius: 50%;
        background: transparent;
        color: inherit;
        cursor: pointer;
        opacity: 0.7;
    }
    [ui="tag"] > [ui-removable-trigger]:hover { opacity: 1; background: color-mix(in oklab, var(--_tone) 18%, transparent); }
    [ui="tag"] > [ui-removable-trigger]:focus-visible { outline: none; opacity: 1; box-shadow: 0 0 0 2px var(--ui-focus-ring); }
}


@layer platform-ui.primitives {
    /* The shared control look lives in input.css. */
    [ui="textarea"] { display: block; field-sizing: content; max-height: 24lh; }
}