@layer components {
  /* Buttons
   * Default color is brand primary. Variants override --btn-color.
   * Hover/active derived via color-mix() — one color in, all states out.
   */

  .btn {
    --btn-color: var(--color-primary);
    --btn-bg: var(--btn-color);
    --btn-text: white;
    --btn-border-radius: var(--radius);

    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    padding: 0.5em 1.25em;
    min-height: 2.75rem; /* 44px touch target */
    font: inherit;
    font-weight: 500;
    line-height: 1.25;
    color: var(--btn-text);
    background: var(--btn-bg);
    border: 1px solid transparent;
    border-radius: var(--btn-border-radius);
    cursor: pointer;
    text-decoration: none;
    white-space: nowrap;
    transition: background var(--transition-fast), color var(--transition-fast);

    &:hover {
      --btn-bg: color-mix(in oklch, var(--btn-color) 85%, white);
    }

    &:active {
      --btn-bg: color-mix(in oklch, var(--btn-color) 90%, black);
    }

    &:focus-visible {
      outline: 2px solid var(--btn-color);
      outline-offset: 2px;
    }

    &:disabled, &[aria-disabled="true"] {
      opacity: 0.5;
      cursor: not-allowed;
      pointer-events: none;
    }
  }

  /* --- Variants --- */

  .btn--outline {
    --btn-text: var(--btn-color);
    --btn-bg: transparent;
    border-color: var(--btn-color);

    &:hover {
      --btn-bg: color-mix(in oklch, var(--btn-color) 8%, transparent);
    }

    &:active {
      --btn-bg: color-mix(in oklch, var(--btn-color) 14%, transparent);
    }
  }

  .btn--ghost {
    --btn-text: var(--btn-color);
    --btn-bg: transparent;

    &:hover {
      --btn-bg: color-mix(in oklch, var(--btn-color) 8%, transparent);
    }

    &:active {
      --btn-bg: color-mix(in oklch, var(--btn-color) 14%, transparent);
    }
  }

  .btn--danger {
    --btn-color: var(--color-error);
  }

  .btn--secondary {
    --btn-color: var(--color-ink-muted);
    --btn-bg: var(--color-surface);
    --btn-text: var(--color-text);
    border-color: var(--color-border);

    &:hover {
      --btn-bg: color-mix(in oklch, var(--color-surface) 80%, var(--color-border));
    }
  }

  /* --- Sizes --- */

  .btn--sm {
    padding: 0.3em 0.75em;
    min-height: 2.25rem; /* 36px — smaller but still tappable */
    font-size: var(--font-size-small);
  }

  .btn--lg {
    padding: 0.625em 1.75em;
    font-size: 1.125rem;
  }

  /* --- Loading state (spinner via ::after pseudo-element) --- */

  .btn--loading {
    pointer-events: none;
    opacity: 0.7;

    &::after {
      content: "";
      width: 1em;
      height: 1em;
      border: 2px solid currentColor;
      border-right-color: transparent;
      border-radius: var(--radius-full);
      animation: spin 600ms linear infinite;
    }
  }

  /* --- Button group --- */

  .btn-group {
    display: inline-flex;

    & .btn {
      border-radius: 0;

      &:first-child { border-radius: var(--radius) 0 0 var(--radius); }
      &:last-child { border-radius: 0 var(--radius) var(--radius) 0; }
      & + .btn { border-inline-start: 1px solid color-mix(in oklch, var(--btn-text) 20%, transparent); }
    }
  }

  /* --- Circle icon button (icon + screen-reader text) --- */

  .btn:where(:has(.visually-hidden):has(img)),
  .btn:where(:has(.visually-hidden):has(svg)) {
    --btn-border-radius: 50%;
    aspect-ratio: 1;
    padding: 0.5em;
  }
}