@keyframes rotate {
  from { transform: rotate(0deg); }
  to   { transform: rotate(360deg); }
}

@layer components {
  .header-inner {
    padding-block: var(--space-2);
    padding-inline: var(--space-4);
    display: flex;
    justify-content: space-between;
    align-items: center;
    position: relative;
    background: var(--color-surface);
    backdrop-filter: blur(4px);

    @media (min-width: 48rem) {
      padding-block: var(--space-3);
      padding-inline: var(--space-8);
    }
  }

  .header-divider {
    position: absolute;
    inset-block-end: 0;
    inset-inline: var(--space-4);
    block-size: 2px;
    background: var(--color-border);

    @media (min-width: 48rem) {
      inset-inline: var(--space-8);
    }
  }

  .breadcrumb {
    display: flex;
    align-items: center;
    gap: var(--space-1);
    font-size: var(--text-sm);
    color: var(--color-text-muted);

    a {
      color: var(--color-text-muted);
      text-decoration: underline;

      &:hover {
        opacity: 0.8;
        text-decoration: none;
      }
    }
  }

  .site-nav {
    display: flex;
    align-items: center;
    gap: var(--space-4);

    @media (min-width: 48rem) {
      gap: var(--space-8);
    }

    a {
      font-size: var(--text-sm);
      color: var(--color-text-muted);
      text-decoration: underline;

      &:hover {
        opacity: 0.8;
      }
    }
  }

  .toggle-group {
    display: flex;
    align-items: center;
    gap: var(--space-1);

    @media (min-width: 48rem) {
      gap: var(--space-2);
    }

    svg {
      inline-size: 1rem;
      block-size: 1rem;

      @media (min-width: 48rem) {
        inline-size: 1.25rem;
        block-size: 1.25rem;
      }
    }
  }

  .theme-toggle {
    --toggle-height:     1.5rem;
    --toggle-width:      2.5rem;
    --toggle-padding:    0.125rem;
    --toggle-thumb-size: calc(var(--toggle-height) - var(--toggle-padding) * 2);
    --toggle-translate:  calc(var(--toggle-width) - var(--toggle-thumb-size) - var(--toggle-padding) * 2);
    --toggle-bg:         var(--color-border-light);

    position: relative;
    display: inline-block;
    inline-size: var(--toggle-width);
    block-size: var(--toggle-height);
    background: var(--toggle-bg);
    border-radius: 9999px;
    cursor: pointer;
    transition: background 300ms var(--ease-out-expo);

    @media (min-width: 48rem) {
      --toggle-height: 1.75rem;
      --toggle-width:  3.5rem;
    }

    &:has(input:checked) {
      --toggle-bg: var(--color-accent-muted);
    }

    input {
      display: none;
    }
  }

  .theme-toggle__thumb {
    position: absolute;
    inset-block-start: var(--toggle-padding);
    inset-inline-start: var(--toggle-padding);
    inline-size: var(--toggle-thumb-size);
    block-size: var(--toggle-thumb-size);
    background: var(--color-canvas);
    border-radius: 9999px;
    transition: transform 300ms var(--ease-out-expo);

    .theme-toggle:has(input:checked) & {
      transform: translateX(var(--toggle-translate));
    }
  }

  .simulation-rotating {
    color: var(--color-text-muted);
    animation: rotate 3s linear infinite;
  }

  .simulation-static {
    color: var(--color-accent);
    animation: none;
  }
}