/* The site's header and footer (PLAN.md D-028, D-030, D-032, D-036). Split out of
   site.css, which holds the page and its blocks, when the two together passed the size
   limit. The same rule: only custom properties, no literal colours, pixel values, fonts or
   shadows. Linked after site.css and before sections.css, the order these rules had when
   they were one file. */

/* Site chrome (PLAN.md D-028, D-030)

   What the chrome LOOKS like lives here; what it measures lives in sections.css, next to
   the .block rule that sets those properties. Two rules of mine sat here setting
   --section-rhythm and --section-width and neither ever applied: .block sets both, the
   selectors weigh the same, and sections.css is linked second. The header's height did
   fall when I wrote the first one, so I believed it — but it fell because a bar holds less
   than a band of content. Measured afterwards: the header was still taking --space-xl. */

.site-header {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-m) var(--space-l);
  align-items: center;
  justify-content: space-between;
}

.site-logo {
  display: inline-flex;
  text-decoration: none;
}

/* Held by its height so a wide logo and a square one sit on the same line, and sized in
   ems so the character's own scale carries it. */
.site-logo img {
  display: block;
  block-size: 2.5em;
  inline-size: auto;
  border-radius: 0;
}

.site-nav ul,
.site-footer-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-m);
  margin: 0;
  padding: 0;
  list-style: none;
}

/* A navigation link keeps its colour at rest and gains the underline on hover and focus.
   The reverse — grey until touched — is the "no control is ever invisible at rest" rule
   broken in the quietest possible way (CLAUDE.md). */
.site-nav a,
.site-footer-nav a {
  text-decoration: none;
}

.site-nav a:hover,
.site-nav a:focus-visible,
.site-footer-nav a:hover,
.site-footer-nav a:focus-visible {
  text-decoration: underline;
}

.site-nav-children {
  display: none;
}

.site-header-action {
  margin: 0;
}

.site-footer {
  display: grid;
  gap: var(--space-s);
}

.site-footer-text {
  color: var(--section-muted);
}

/* The switcher sits in the footer now, so it no longer carries the standalone padding it
   had when the layout drew it on its own. */
.site-footer .locale-switcher {
  padding-block: 0;
}

.site-small-print {
  margin: 0;
  color: var(--section-muted);
  font-size: var(--text-sm);
}

/* THE CHROME'S LOOK (PLAN.md D-032, D-036). Every value is a closed-set class drawn from
   the tokens: density, a rule under the header, logo size, and the header's and footer's
   arrangements. Surfaces are the sections' own (sections.css), so contrast is the
   palette's guarantee here as everywhere. */

.site-header.density-compact { padding-block: var(--space-s); }
.site-header.density-normal { padding-block: var(--space-m); }
.site-header.density-roomy { padding-block: var(--space-l); }
.site-footer.density-compact { padding-block: var(--space-m); }
.site-footer.density-normal { padding-block: var(--space-l); }
.site-footer.density-roomy { padding-block: var(--space-xl); }

.block-header:has(.has-rule) {
  border-block-end: var(--border-width) solid var(--section-border);
}

.logo-small .site-logo img { block-size: 2em; }
.logo-medium .site-logo img { block-size: 2.75em; }
.logo-large .site-logo img { block-size: 3.75em; }

/* The page being drawn, and the parent it sits under: marked by a rule under the words,
   so it reads the same on every surface without a colour of its own. */
.site-nav a[aria-current="page"],
.site-nav .is-current-parent > a,
.site-footer-nav a[aria-current="page"] {
  text-decoration: underline;
  text-decoration-thickness: 0.12em;
  text-underline-offset: 0.35em;
}

/* Centred: the name above, the navigation on one axis under it. */
.layout-centred .site-header {
  flex-direction: column;
  justify-content: center;
  text-align: center;
}

.layout-centred .site-nav ul {
  justify-content: center;
}

/* Sticky: always within reach, over whatever scrolls beneath on its own surface. */
.block-header.layout-sticky {
  position: sticky;
  top: 0;
  z-index: 10;
}

/* Transparent: laid over the first section, taking that section's colours rather than
   painting its own — which is what makes it readable over any surface a hero can have.
   The first section gains the header's room above its own rhythm, so nothing sits under
   the bar. */
.page {
  position: relative;
}

.block-header.layout-transparent {
  position: absolute;
  inset-inline: 0;
  top: 0;
  z-index: 10;
  background: transparent;
}

.page:has(> .block-header.layout-transparent) > main > .block:first-child {
  padding-block-start: calc(var(--section-rhythm) + var(--space-3xl));
}

.page:has(> main > .block:first-child:is(.surface-contrast, .surface-image)) > .block-header.layout-transparent {
  --section-text: var(--color-on-contrast);
  --section-muted: var(--color-muted-on-contrast);
  --section-link: var(--color-on-contrast);
  --section-border: var(--color-muted-on-contrast);
  --section-button-bg: var(--color-on-contrast);
  --section-button-text: var(--color-contrast);
}

.page:has(> main > .block:first-child.surface-gradient) > .block-header.layout-transparent {
  --section-text: var(--color-on-gradient);
  --section-muted: var(--color-on-gradient);
  --section-link: var(--color-on-gradient);
  --section-border: var(--color-on-gradient);
  --section-button-bg: var(--color-on-gradient);
  --section-button-text: var(--color-gradient-start);
}

.page:has(> main > .block:first-child.surface-tinted) > .block-header.layout-transparent {
  --section-card: var(--color-background);
}

/* Footer in columns: the owner's words beside the navigation, the small print under both. */
.layout-columns .site-footer {
  grid-template-columns: minmax(0, 2fr) minmax(0, 1fr);
  column-gap: var(--space-xl);
  align-items: start;
}

.layout-columns .site-footer-nav ul {
  flex-direction: column;
  gap: var(--space-xs);
}

.layout-columns .site-footer .locale-switcher,
.layout-columns .site-small-print {
  grid-column: 1 / -1;
}

/* Submenus. Without a script they are listed under their parent, smaller and indented, so
   nothing is out of reach. With one (site-nav.js), each opens from its own button and
   drops below its parent on its own surface. */
.site-nav li {
  position: relative;
}

.site-nav-children {
  display: block;
  padding-inline-start: var(--space-m);
  font-size: var(--text-sm);
}

.site-nav-children li + li {
  margin-block-start: var(--space-xs);
}

.nav-ready .site-nav-children {
  display: none;
}

.nav-ready .site-nav li.is-open > .site-nav-children {
  display: block;
  position: absolute;
  top: 100%;
  inset-inline-start: 0;
  z-index: 11;
  min-inline-size: 12em;
  margin-block-start: var(--space-xs);
  padding: var(--space-s) var(--space-m);
  background: var(--section-bg);
  border: var(--border-width) solid var(--section-border);
  border-radius: var(--radius-m);
  box-shadow: var(--shadow-m);
}

/* The controls a script adds: legible at rest, in the section's own ink (CLAUDE.md). */
.site-nav-more,
.site-nav-toggle {
  padding: var(--space-xs) var(--space-s);
  background: transparent;
  border: var(--border-width) solid var(--section-border);
  border-radius: var(--radius-s);
  color: var(--section-text);
  font: inherit;
  line-height: 1;
  cursor: pointer;
}

.site-nav-more {
  margin-inline-start: 0.2em;
  padding: 0.1em 0.2em;
  border-color: transparent;
  font-size: var(--text-sm);
}

/* The chevron turns when its submenu is open, so the state is visible, not only spoken. */
.site-nav-more[aria-expanded="true"] span {
  display: inline-block;
  transform: rotate(180deg);
}

.site-header-action .button {
  white-space: nowrap;
}

.site-nav > ul > li {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
}

.site-nav-toggle {
  display: none;
}

@media (max-width: 40rem) {
  /* On a narrow screen the bar becomes a stack: a logo, its navigation and a button do
     not share a line at this width without one of them being squeezed to nothing. */
  .site-header {
    justify-content: flex-start;
  }

  /* The real mobile menu (D-032): one button, and the navigation folded under it until it
     is opened. Only once site-nav.js has run — without it, the navigation wraps openly. */
  .nav-ready .site-nav-toggle {
    display: inline-block;
    margin-inline-start: auto;
    padding: var(--space-xs) var(--space-m);
    border-radius: var(--radius-button);
  }

  /* One shape on a phone, whatever the arrangement on a wide screen: the name and the
     Menu button on one line, and the navigation and the call to action folded under it.
     A centred column there scattered three controls down the screen. */
  .layout-centred .nav-ready.site-header,
  .nav-ready.site-header {
    flex-direction: row;
    flex-wrap: wrap;
    justify-content: space-between;
    align-items: center;
    text-align: start;
  }

  .nav-ready .site-nav,
  .nav-ready .site-header-action {
    display: none;
    flex-basis: 100%;
  }

  .nav-ready.nav-open .site-nav,
  .nav-ready.nav-open .site-header-action {
    display: block;
  }

  .layout-centred .nav-ready .site-nav ul {
    justify-content: flex-start;
  }

  .nav-ready .site-nav ul {
    flex-direction: column;
    gap: var(--space-s);
  }

  .nav-ready .site-nav li.is-open > .site-nav-children {
    position: static;
    margin-block-start: var(--space-xs);
    box-shadow: none;
  }

  .layout-columns .site-footer {
    grid-template-columns: minmax(0, 1fr);
  }
}