*, *::before, *::after {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
  }

  /* Neutralise the UA stylesheet for [popover]. PositionController promotes
     floating panels to the top layer, and the UA rules for a popover include
     a solid border, padding, a canvas background and inset:0/margin:auto —
     enough to inflate a measured panel by 14px and to paint a border no
     component asked for. :where() keeps this at zero specificity so it beats
     the UA origin but loses to every rule a component writes for itself. */
  :where([popover]) {
    border: 0;
    padding: 0;
    margin: 0;
    inset: auto;
    width: auto;
    height: auto;
    background: none;
    color: inherit;
    overflow: visible;
  }

  :host {
    transition: opacity var(--transition-fast);

    
    /* Generated from shared/tokens.js by scripts/generate/host-tokens.js. */
    /* Do not edit by hand — edit the token tree instead. */

    --font-body: var(--font-body-family, 'Host Grotesk'), var(--font-body-fallback, system-ui, sans-serif);
    --font-label: var(--font-label-family, 'Tomorrow'), var(--font-label-fallback, system-ui, -apple-system, Segoe UI, sans-serif);
    --font-mono: var(--font-mono-family, 'JetBrains Mono'), var(--font-mono-fallback, ui-monospace, monospace);
    --font-quote: var(--font-quote-family, Georgia), var(--font-quote-fallback, serif);
    --font-display: var(--font-display-family, var(--font-body-family, 'Host Grotesk')), var(--font-display-fallback, var(--font-body-fallback, system-ui, sans-serif));
    --font-accent: var(--font-label);

    /* Private mirrors: components read these, consumers override --text-*. */
    --_text-xs: var(--text-xs, 12px);
    --_text-sm: var(--text-sm, 16px);
    --_text-md: var(--text-md, 17px);
    --_text-lg: var(--text-lg, clamp(18px, 1.5vw, 20px));
    --_text-xl: var(--text-xl, clamp(22px, 2.5vw, 26px));
    --_text-2xl: var(--text-2xl, clamp(28px, 3vw, 36px));
    --_text-3xl: var(--text-3xl, clamp(36px, 5vw, 52px));

    --display-xl-size: var(--_text-3xl);
    --display-xl-weight: var(--font-display-weight, 500);
    --display-xl-spacing: -1px;
    --heading-size: var(--_text-xl);
    --heading-weight: var(--font-display-weight, 500);
    --heading-lh: 1.2;
    --body-size: var(--_text-md);
    --body-weight: var(--font-body-weight, 500);
    --body-lh: 1.7;
    --wordmark-size: clamp(20px, 2.5vw, 28px);
    --wordmark-weight: var(--font-display-weight, 500);
    --wordmark-spacing: clamp(8px, 1.2vw, 14px);
    --section-title-size: var(--_text-xs);
    --section-title-weight: var(--font-label-weight, 600);
    --section-title-spacing: 2px;
    --ui-accent-size: 16px;
    --ui-accent-weight: var(--font-label-weight, 600);
    --ui-accent-spacing: 0.5px;
    --code-size: 14px;
    --code-lh: 1.8;
    --label-inline-size: 10px;
    --label-inline-spacing: 0.75px;

    /* Spacing */
    --space-xs: 4px;
    --space-sm: 8px;
    --space-md: 16px;
    --space-lg: 24px;
    --space-xl: 40px;
    --space-2xl: 64px;
    --space-3xl: 96px;
    --space-4xl: 128px;

    /* Radii */
    --radius-xs: 2px;
    --radius-sm: 4px;
    --radius-md: 10px;
    --radius-lg: 14px;
    --radius-xl: 20px;
    --radius-full: 9999px;

    /* Transitions and motion */
    --transition-fast: var(--duration-fast) var(--ease-standard);
    --transition-base: var(--duration-base) var(--ease-standard);
    --transition-slow: var(--duration-slow) var(--ease-standard);
    --transition-enter: var(--duration-enter) var(--ease-out);
    --transition-exit: var(--duration-exit) var(--ease-in);
    --ease-standard: cubic-bezier(0.4, 0, 0.2, 1);
    --ease-out: cubic-bezier(0.16, 1, 0.3, 1);
    --ease-in: cubic-bezier(0.7, 0, 0.84, 0);
    --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
    --duration-fast: 120ms;
    --duration-base: 200ms;
    --duration-slow: 400ms;
    --duration-enter: 500ms;
    --duration-exit: 300ms;
    --ease-out-expo: var(--ease-out);
    --ease-in-out: var(--ease-standard);

    /* Z-index */
    --z-base: 0;
    --z-dropdown: 1000;
    --z-tooltip: 1100;
    --z-overlay: 1200;
    --z-modal: 1300;
    --z-toast: 1400;
    --z-max: 9999;

    /* Glow and focus */
    --glow-xs: 0 0 6px rgba(var(--accent-primary-rgb), 0.3);
    --glow-sm: 0 0 8px rgba(var(--accent-primary-rgb), 0.3);
    --glow-md: 0 0 12px rgba(var(--accent-primary-rgb), 0.25);
    --glow-status: 0 0 12px rgba(var(--_status-rgb), var(--glow-status-alpha, 0.15));
    --glow-status-alpha: 0.15;
    --glow-hover: 0 0 12px rgba(var(--accent-primary-rgb), 0.15);
    --focus-ring: 0 0 0 1px rgba(var(--accent-primary-rgb),0.25);
    --focus-glow: 0 0 0 1px rgba(var(--accent-primary-rgb),0.2), 0 0 6px rgba(var(--accent-primary-rgb),0.35), 0 0 16px rgba(var(--accent-primary-rgb),0.2), 0 0 40px rgba(var(--accent-secondary-rgb),0.12);
    --focus-error: 0 0 0 2px var(--surface-base), 0 0 0 4px var(--color-error), 0 0 16px rgba(var(--color-error-rgb), 0.2);
    --focus-inset: inset 0 0 0 2px var(--interactive);
    --focus-thumb: 0 0 8px rgba(var(--interactive-rgb), 0.5), 0 0 20px rgba(var(--interactive-rgb), 0.25);

    /* Semantic aliases */
    --interactive: var(--accent-primary);
    --interactive-rgb: var(--accent-primary-rgb);
    --interactive-hover: var(--glow-hover);
    --interactive-active: var(--glow-primary);
    --interactive-focus: var(--focus-glow);
    --interactive-focus-ring: var(--focus-ring);
    --interactive-focus-error: var(--focus-error);
    --interactive-focus-inset: var(--focus-inset);
    --interactive-focus-thumb: var(--focus-thumb);
    --interactive-muted: var(--text-ghost);
    --surface-base: var(--bg-deep);
    --surface-primary: var(--bg-surface);
    --surface-raised: var(--bg-card);
    --surface-overlay: var(--bg-elevated);
    --surface-hover: var(--bg-hover);
    --divider: var(--border-subtle);
    --on-accent: var(--surface-base);

    /* Interactive and layout */
    --touch-min: 24px;
    --touch-pad: 4px;
    --max-width: 1120px;
    --max-width-sm: 720px;
    --nav-height: 64px;
    --nav-row-inset: var(--space-sm);

  }

  
  @media (pointer: coarse) {
    :host {
      --touch-min: 36px;
      --touch-pad: 8px;
    }
  }


  /* Reduced motion, once, for every component that adopts these styles.

     This was copy-pasted verbatim into sixty-nine component files while fifteen
     animating components had no guard at all — which is the usual outcome when
     a cross-cutting rule is a convention rather than a place. Components keep
     their own blocks only for what this cannot express: scroll-behavior,
     animation-play-state, a transform that must be neutralised rather than
     shortened.

     0.01ms rather than "animation: none" on purpose. A component that removes
     itself on animationend — the exiting toast and snackbar both do — would
     wait forever for an event that a canceled animation never fires. A
     duration this short is imperceptible and still completes. */
  @media (prefers-reduced-motion: reduce) {
    :host *,
    :host *::before,
    :host *::after {
      animation-duration: 0.01ms !important;
      animation-iteration-count: 1 !important;
      transition-duration: 0.01ms !important;
    }
  }

  /* ── Primary ── */
  :host([variant="primary"]) .btn,
  :host([variant="primary"]) .btn-slot::slotted(a) {
    background: var(--interactive);
    color: var(--on-accent);
    border-color: var(--interactive);
  }
  :host([variant="primary"]) .btn:hover,
  :host([variant="primary"]) .btn-slot::slotted(a:hover) {
    box-shadow: var(--interactive-active);
  }

  /* ── Secondary ── */
  :host([variant="secondary"]) .btn,
  :host([variant="secondary"]) .btn-slot::slotted(a) {
    background: transparent;
    color: var(--text-primary);
    border-color: var(--border-default);
  }
  :host([variant="secondary"]) .btn:hover,
  :host([variant="secondary"]) .btn-slot::slotted(a:hover) {
    border-color: var(--interactive);
    color: var(--interactive);
    box-shadow: 0 0 20px rgba(var(--interactive-rgb), 0.15);
  }

  /* ── Ghost ── */
  :host([variant="ghost"]) .btn,
  :host([variant="ghost"]) .btn-slot::slotted(a) {
    background: transparent;
    color: var(--text-muted);
    border-color: transparent;
  }
  :host([variant="ghost"]) .btn:hover,
  :host([variant="ghost"]) .btn-slot::slotted(a:hover) {
    color: var(--text-primary);
    background: var(--surface-hover);
  }

  /* ── Focus ── */
  .btn:focus-visible { outline: none; box-shadow: var(--interactive-focus); }
  .btn-slot::slotted(a:focus-visible) { outline: none; box-shadow: var(--interactive-focus); }

  /* ── Disabled ── */
  :host([disabled]) .btn,
  :host([disabled]) .btn-slot::slotted(a) { opacity: 0.5; cursor: not-allowed; pointer-events: none; }

  /* Circular. An icon-only control has no text to give it a reading direction,
     so a square is arbitrary about its corners in a way a circle is not; it
     also separates the bare-glyph controls from the labeled, rectangular ones
     at a glance. This is the shape arc-theme-toggle already had, now applied to
     both rather than to one of them. */
  .btn:not(.btn--has-text),
  .btn-slot::slotted(a) { border-radius: var(--radius-full); }

  .btn:not(.btn--has-text) { aspect-ratio: 1; }

  .btn:not(.btn--has-text),
  .btn-slot::slotted(a) { min-width: var(--touch-min); min-height: var(--touch-min); }

  /* The default arm is keyed on "not the others" so an unrecognized size lands
     on it rather than on no rule at all — see check-enum-fallbacks.js. The
     explicit [size="md"] selector stays so prism can infer the union. */
  :host(:not([size="lg"]):not([size="sm"]):not([size="xs"])) .btn:not(.btn--has-text),
  :host(:not([size="lg"]):not([size="sm"]):not([size="xs"])) .btn-slot::slotted(a),
  :host([size="md"]) .btn:not(.btn--has-text),
  :host([size="md"]) .btn-slot::slotted(a) { width: 36px; height: 36px; }

  :host([size="xs"]) .btn:not(.btn--has-text),
  :host([size="xs"]) .btn-slot::slotted(a) { width: 28px; height: 28px; }

  :host([size="sm"]) .btn:not(.btn--has-text),
  :host([size="sm"]) .btn-slot::slotted(a) { width: 32px; height: 32px; }

  :host([size="lg"]) .btn:not(.btn--has-text),
  :host([size="lg"]) .btn-slot::slotted(a) { width: 44px; height: 44px; }

      :host { display: inline-flex; }
      :host([disabled]) { pointer-events: none; }

      /* Anchor-adoption form: a lone slotted <a> becomes the control and takes
         the same box styling as .btn — see shared/anchor-adoption.js. The
         adopted anchor is always treated as icon-only, since any text the
         consumer wants lives inside their own anchor. */
      .btn,
      .btn-slot::slotted(a) {
        display: inline-flex;
        align-items: center;
        justify-content: center;
        gap: var(--space-xs);
        border: 1px solid transparent;
        border-radius: var(--radius-md);
        cursor: pointer;
        transition:
          background var(--transition-base),
          border-color var(--transition-base),
          box-shadow var(--transition-base),
          color var(--transition-base),
          transform 120ms var(--ease-out-expo);
        text-decoration: none;
        box-sizing: border-box;
        color: inherit;
      }

      /* With text */
      .btn--has-text {
        font-family: var(--font-label);
        font-weight: var(--font-label-weight, 600);
        text-transform: uppercase;
        --_ls: 1.5px;
        letter-spacing: var(--_ls);
        white-space: nowrap;
      }

      .btn__text {
        line-height: 1;
        /* letter-spacing also lands after the final letter, and that trailing
           space is inside the box being centered — so the word rendered half of
           it, 0.75px, to the left of centre. Pulled back off the end here, at
           the cause: the box then matches the ink and every size centres
           correctly, where compensating with padding would have meant patching
           each of the four size rules separately.
           arc-navigation-menu does the same correction with asymmetric padding
           instead, because its label is a bare text node with no element to
           hang a margin on. */
        margin-inline-end: calc(var(--_ls) * -1);
      }

      /* Sizes — icon-only: see iconBoxStyles in ../button-styles.js, shared with
         arc-theme-toggle so the two cannot drift apart in a top bar. */

      /* Sizes — with text */
      .btn--has-text { min-height: var(--touch-min); }
      :host([size="xs"]) .btn--has-text { padding: var(--space-xs) var(--space-sm); font-size: var(--_text-xs); }
      :host([size="sm"]) .btn--has-text { padding: calc(var(--space-xs) + 2px) calc(var(--space-sm) + 2px); font-size: var(--_text-xs); }
      :host(:not([size="lg"]):not([size="sm"]):not([size="xs"])) .btn--has-text,
      :host([size="md"]) .btn--has-text { padding: var(--space-xs) var(--space-sm); font-size: var(--_text-xs); }
      :host([size="lg"]) .btn--has-text { padding: var(--space-sm) var(--space-md); font-size: var(--_text-xs); }

      /* Default → ghost */
      :host(:not([variant="primary"]):not([variant="secondary"])) .btn,
      :host(:not([variant="primary"]):not([variant="secondary"])) .btn-slot::slotted(a) {
        background: transparent;
        color: var(--text-muted);
        border-color: transparent;
      }
      :host(:not([variant="primary"]):not([variant="secondary"])) .btn:hover,
      :host(:not([variant="primary"]):not([variant="secondary"])) .btn-slot::slotted(a:hover) {
        color: var(--text-primary);
        background: var(--surface-hover);
      }

      /* :active scale */
      :host(:not([variant="primary"]):not([variant="secondary"])) .btn:active,
      :host(:not([variant="primary"]):not([variant="secondary"])) .btn-slot::slotted(a:active),
      :host([variant="ghost"]) .btn:active,
      :host([variant="ghost"]) .btn-slot::slotted(a:active) {
        transform: scale(0.93);
        background: var(--surface-overlay);
      }
      :host([variant="secondary"]) .btn:active,
      :host([variant="secondary"]) .btn-slot::slotted(a:active) {
        transform: scale(0.93);
        background: rgba(var(--interactive-rgb), 0.05);
      }
      :host([variant="primary"]) .btn:active,
      :host([variant="primary"]) .btn-slot::slotted(a:active) {
        transform: scale(0.93);
        box-shadow: 0 0 8px rgba(var(--interactive-rgb), 0.5);
      }

      /* IconButton secondary uses text-secondary instead of text-primary */
      :host([variant="secondary"]) .btn,
      :host([variant="secondary"]) .btn-slot::slotted(a) {
        color: var(--text-secondary);
      }

      /* IconButton secondary hover uses smaller glow */
      :host([variant="secondary"]) .btn:hover,
      :host([variant="secondary"]) .btn-slot::slotted(a:hover) {
        box-shadow: 0 0 16px var(--accent-primary-ring);
      }