@layer components {
  .site-header {
    align-items: center;
    column-gap: var(--header-gap, var(--inline-space-half));
    display: grid;
    grid-template-areas:
      ". brand messages"
      "nav nav nav";
    grid-template-columns: 1fr auto 1fr;

    @media (width >= 960px) {
      grid-template-areas: ". brand nav messages";
      grid-template-columns: 1fr auto auto 1fr;
    }
  }

  .header:has(> .site-header) {
    align-items: center;
    row-gap: 0;

    /* As wide as a wide page inside #main's padding, so the actions end where the page does. */
    inline-size: 100%;
    margin-inline: auto;
    max-inline-size: calc(var(--header-size, 65rem) + var(--main-padding) * 2);

    /* header.css sizes the action columns for icon circles; from 640 up ours carry a label, so the sides take their content and stay equal while there is room. */
    @media (width >= 640px) {
      --header-actions-width: auto;
      --header-btn-size: 2.5rem;

      column-gap: var(--header-gap);
      grid-template-columns: 1fr fit-content(50%) 1fr;
    }
  }

  @media (width >= 640px) {
    .header__actions {
      font-size: var(--text-normal);
    }

    .header__actions > .popup-anchor > .btn--circle {
      --btn-size: var(--header-btn-size);
    }

    /* buttons.css makes a circle of any button with an aria-label and an icon, the label stacked on the icon. */
    .header__actions .btn--circle-mobile[aria-label] {
      --btn-gap: var(--inline-space);
      --btn-padding: 0 1.1em;
      --icon-size: var(--btn-icon-size, 1.3em);

      aspect-ratio: auto;
      block-size: auto;
      display: inline-flex;
      inline-size: auto;
      justify-content: center;
      min-block-size: var(--header-btn-size);
      white-space: nowrap;
    }
  }

  /* The circle the header's columns are sized for. */
  @media (width < 640px) {
    .header__actions .btn--circle-mobile {
      --btn-size: var(--header-btn-size);
    }
  }

  .header .header__title {
    font-size: var(--text-x-large);
    font-weight: 800;
    letter-spacing: -0.024em;
    line-height: 1.15;
  }

  /* With the title and actions in the strip, the header keeps its sections row alone. */
  .header:has(> .site-header):not(:has(.header__title, .header__actions)) {
    grid-template-areas: "menu menu menu";
  }

  /* Spanning the header's columns, its content would hold their width against the title's. */
  .header > .site-header {
    contain: inline-size;
    grid-area: menu;
  }

  .site-header__brand {
    align-items: center;
    display: inline-flex;
    gap: var(--inline-space-half);
    grid-area: brand;
    justify-content: center;
    min-inline-size: 0;
  }

  .site-header__logo,
  .site-header__account-logo {
    block-size: var(--site-header-logo-size, 2.5rem);
    border-radius: var(--radius-lg);
    display: block;
    inline-size: auto;
  }

  .site-header__account-logo {
    border-radius: var(--radius-md);
    flex-shrink: 1;
    min-inline-size: 0;
    object-fit: contain;
  }

  .public .site-header__logo {
    border-radius: var(--radius-md);
  }

  .site-header__sections {
    display: contents;
  }

  /* header.css places every nav in the header's menu area and centres it; ours sits inside the site header's own grid. */
  .header .site-header__nav {
    grid-area: nav;
    margin-inline: 0;
    min-inline-size: 0;
  }

  /* One row, so the last section never wraps alone. */
  .site-header__list {
    align-items: center;
    display: flex;
    gap: var(--header-gap, var(--inline-space-half));
    justify-content: center;
    list-style: none;
    margin: 0;
    padding: 0;
  }

  .site-header__item {
    flex: none;
  }

  .site-header__link {
    --btn-background: transparent;
    --btn-border-size: 0;
    --btn-padding: 0.5em 0.75em;

    white-space: nowrap;

    @media (any-hover: hover) {
      &:hover {
        --btn-background: var(--color-ink-lighter);
      }
    }

    &[aria-current="page"],
    &[aria-expanded="true"] {
      --btn-background: var(--color-ink-lightest);
    }
  }

  .site-header__messages {
    grid-area: messages;
    justify-self: end;
  }

  .site-header__messages:not(.site-header__messages--unread) .unread-dot {
    display: none;
  }

  /* On a phone the brand sits between the actions, the sections take a row of their own and the title keeps the full width. */
  @media (width < 640px) {
    .header--mobile-actions-stack:has(.site-header__sections) {
      --site-header-logo-size: var(--header-btn-size);

      grid-template-areas:
        "actions-start menu actions-end"
        "sections sections sections"
        "title title title";

      &:not(:has(.header__title, .header__actions)) {
        grid-template-areas:
          "actions-start menu actions-end"
          "sections sections sections";
      }

      > .site-header {
        display: contents;
      }

      .site-header__brand {
        grid-area: menu;
      }

      /* Spanning the header's columns, the row would hold their width against the brand's. */
      .site-header__sections {
        align-items: center;
        contain: inline-size;
        display: flex;
        gap: var(--header-gap);
        grid-area: sections;
        justify-content: center;
      }

      .site-header__nav {
        flex: 0 1 auto;
      }

      /* The row scrolls sideways when the sections do not fit. */
      .site-header__list {
        justify-content: safe center;
        overflow-x: auto;
        overscroll-behavior-x: contain;
        scrollbar-width: none;
      }

      .site-header__link {
        --btn-padding: 0.5em;
      }

      /* With four links and the messages toggle, as an owner has, the row takes the header's side padding and the
         links a smaller size, so all five fit at 375px. Narrower screens still scroll. */
      .site-header__sections:has(.site-header__item:nth-child(4)) {
        gap: 0;
        margin-inline: calc(0.25rem - var(--main-padding));

        .site-header__list {
          gap: 0;
        }

        .site-header__link {
          --btn-padding: 0.5em 0.3em;
          --text-small: var(--text-x-small);
        }
      }

      .site-header__messages {
        flex: none;
      }
    }
  }
}