:root {
  --bg: #f7f7f5;
  --text: #1c1e21;
  --muted: #5f6368;
  --accent: #1f5fa8;
  --border: #d9d9d4;
  --img-bg: transparent;
  color-scheme: light;
}

/* Dark colours: used when the system is set to dark, unless the visitor chose light ... */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #15171a;
    --text: #ececec;
    --muted: #a0a4a8;
    --accent: #7db4f0;
    --border: #33373c;
    --img-bg: #fff;
    color-scheme: dark;
  }
}

/* ... and when the visitor chose dark with the button. Keep both blocks the same. */
:root[data-theme="dark"] {
  --bg: #15171a;
  --text: #ececec;
  --muted: #a0a4a8;
  --accent: #7db4f0;
  --border: #33373c;
  --img-bg: #fff;
  color-scheme: dark;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  line-height: 1.5;
}

a {
  color: var(--accent);
}

header {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px 24px;
  padding: 16px 24px;
  border-bottom: 1px solid var(--border);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  font-weight: 700;
  font-size: 1.125rem;
  color: var(--text);
  text-decoration: none;
}

.brand img {
  width: 48px;
  height: 48px;
  /* The logo is drawn for any background, so it needs no white backing in dark mode. */
  background: transparent;
}

.breadcrumb {
  margin-bottom: 16px;
  font-size: 0.875rem;
  color: var(--muted);
}

.breadcrumb a {
  color: var(--muted);
}

/* Page links in a column on the left of the content. */
.page {
  flex: 1;
  display: flex;
  width: 100%;
  max-width: 68rem;
  margin: 0 auto;
}

.main-nav {
  display: flex;
  flex-direction: column;
  flex: none;
  width: 14rem;
  padding: 32px 0 32px 24px;
  /* Stays in view while scrolling long pages. */
  position: sticky;
  top: 0;
  align-self: flex-start;
}

.main-nav a {
  padding: 6px 12px;
  color: var(--muted);
  text-decoration: none;
  border-left: 2px solid var(--border);
}

.main-nav a:hover {
  color: var(--text);
}

.main-nav a[aria-current] {
  color: var(--text);
  font-weight: 600;
  border-left-color: var(--accent);
}

/* Sub-pages of the open section, indented by level. */
.main-nav a.sub {
  padding-top: 4px;
  padding-bottom: 4px;
  font-size: 0.875rem;
  font-weight: 400;
  line-height: 1.35;
  border-left-color: var(--border);
}

.main-nav a.level-1 {
  padding-left: 24px;
}

.main-nav a.level-2 {
  padding-left: 36px;
}

.main-nav a.level-3 {
  padding-left: 48px;
}

.main-nav a.sub[aria-current] {
  color: var(--text);
}

.main-nav a.sub[aria-current="page"] {
  font-weight: 600;
  border-left-color: var(--accent);
}

/* On small screens the list moves above the content, still one link per line. */
@media (max-width: 640px) {
  .page {
    flex-direction: column;
  }

  .main-nav {
    position: static;
    width: auto;
    padding: 16px 24px 0;
  }
}

.lang-switch {
  display: flex;
  margin-left: auto;
  border: 1px solid var(--border);
  border-radius: 6px;
  overflow: hidden;
}

.lang-switch a {
  padding: 6px 12px;
  color: var(--muted);
  font-size: 0.875rem;
  text-decoration: none;
}

.lang-switch a + a {
  border-left: 1px solid var(--border);
}

.lang-switch a[aria-current="true"] {
  background: var(--accent);
  color: var(--bg);
}

.theme-toggle {
  width: 34px;
  height: 34px;
  padding: 0;
  border: 1px solid var(--border);
  border-radius: 6px;
  background: transparent;
  color: var(--muted);
  font: inherit;
  line-height: 1;
  cursor: pointer;
}

.theme-toggle:hover {
  color: var(--text);
}

main {
  flex: 1;
  min-width: 0;
  max-width: 52rem;
  padding: 32px 24px;
}

h1 {
  margin: 0 0 24px;
  font-size: 2rem;
  line-height: 1.15;
}

h2 {
  margin: 32px 0 8px;
  font-size: 1.375rem;
}

h3 {
  margin: 24px 0 8px;
  font-size: 1.125rem;
}

h4 {
  margin: 20px 0 4px;
  font-size: 1rem;
}

p {
  margin: 0 0 12px;
}

ul,
ol {
  margin: 0 0 12px;
  padding-left: 24px;
}

img {
  max-width: 100%;
  height: auto;
  /* White backing in dark mode so diagrams with transparent backgrounds stay readable. */
  background: var(--img-bg);
}

hr {
  margin: 24px 0;
  border: 0;
  border-top: 1px solid var(--border);
}

code {
  font-size: 0.9em;
}

/* Photo on the left, text beside it (team pages). */
.media {
  display: flow-root;
  margin-bottom: 16px;
}

.media > p:first-child {
  float: left;
  width: 110px;
  margin: 0;
}

.media > :not(:first-child) {
  margin-left: 130px;
}

.media > h2 {
  margin-top: 0;
}

/* Larger photo on a person's own page. */
.media-large > p:first-child {
  width: 160px;
}

.media-large > :not(:first-child) {
  margin-left: 184px;
}

@media (max-width: 480px) {
  .media > p:first-child {
    float: none;
    margin-bottom: 12px;
  }

  .media > :not(:first-child) {
    margin-left: 0;
  }
}

/* Centred figure; the width is set per image in the Markdown. */
img.center {
  display: block;
  margin: 20px auto;
}

.notice {
  padding: 12px 16px;
  border: 1px solid var(--border);
  border-left: 4px solid var(--accent);
  border-radius: 4px;
}

footer {
  display: flex;
  flex-wrap: wrap;
  justify-content: center;
  gap: 4px 20px;
  padding: 16px 24px;
  border-top: 1px solid var(--border);
  font-size: 0.875rem;
  color: var(--muted);
}

footer a {
  color: var(--muted);
}