/* rpi-provision documentation.
 *
 * No web fonts and no framework: system fonts, a two-column shell that
 * collapses on narrow screens, and a palette that follows the reader's
 * light or dark preference. */

:root {
  --bg: #ffffff;
  --bg-sunken: #f6f7f9;
  --bg-code: #f4f5f7;
  --fg: #1c2024;
  --fg-muted: #5b6570;
  --border: #dfe3e8;
  --accent: #9a2c3f;
  --accent-soft: #fbeff1;
  --measure: 46rem;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas,
    "Liberation Mono", monospace;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue",
    Arial, "Noto Sans", "Noto Sans JP", sans-serif;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #14171a;
    --bg-sunken: #1b1f23;
    --bg-code: #1e2328;
    --fg: #e4e7ea;
    --fg-muted: #9aa4ae;
    --border: #2c333a;
    --accent: #f2a0af;
    --accent-soft: #2a1d21;
  }
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.65;
  -webkit-text-size-adjust: 100%;
}

a {
  color: var(--accent);
  text-underline-offset: 0.15em;
}

a:hover {
  text-decoration-thickness: 2px;
}

.skip-link {
  position: absolute;
  left: -9999px;
}

.skip-link:focus {
  left: 1rem;
  top: 0.6rem;
  z-index: 10;
  padding: 0.5rem 0.9rem;
  background: var(--bg);
  border: 1px solid var(--border);
  border-radius: 6px;
}

/* ---------------------------------------------------------- masthead */

.masthead {
  border-bottom: 1px solid var(--border);
  background: var(--bg-sunken);
}

.masthead-inner {
  max-width: 74rem;
  margin: 0 auto;
  padding: 1.1rem 1.5rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1.5rem;
  align-items: baseline;
  justify-content: space-between;
}

.brand {
  color: inherit;
  text-decoration: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.15rem 0.75rem;
  align-items: baseline;
}

.brand-name {
  font-family: var(--mono);
  font-size: 1.15rem;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.brand-tagline,
.repo-link {
  font-size: 0.86rem;
  color: var(--fg-muted);
}

.repo-link {
  text-decoration: none;
  white-space: nowrap;
}

.repo-link:hover {
  color: var(--accent);
  text-decoration: underline;
}

/* ------------------------------------------------------------- shell */

.shell {
  max-width: 74rem;
  margin: 0 auto;
  padding: 0 1.5rem;
  display: grid;
  grid-template-columns: 15rem minmax(0, 1fr);
  gap: 3rem;
  align-items: start;
}

.sidebar {
  position: sticky;
  top: 0;
  padding: 2.25rem 0 2rem;
  max-height: 100vh;
  overflow-y: auto;
}

.nav-section {
  margin: 1.5rem 0 0.4rem;
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--fg-muted);
}

.nav-section:first-child {
  margin-top: 0;
}

.nav-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.nav-list a {
  display: block;
  padding: 0.28rem 0.6rem;
  margin-left: -0.6rem;
  border-radius: 6px;
  color: inherit;
  text-decoration: none;
  font-size: 0.94rem;
}

.nav-list a:hover {
  background: var(--bg-sunken);
  color: var(--accent);
}

.nav-list a[aria-current="page"] {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 600;
}

main {
  padding: 2.25rem 0 4rem;
  min-width: 0;
  max-width: var(--measure);
}

/* ------------------------------------------------------------ typography */

h1,
h2,
h3,
h4 {
  line-height: 1.25;
  letter-spacing: -0.015em;
  scroll-margin-top: 1rem;
}

h1 {
  font-size: 2.1rem;
  margin: 0 0 0.75rem;
}

h2 {
  font-size: 1.4rem;
  margin: 2.75rem 0 0.75rem;
  padding-top: 0.4rem;
  border-top: 1px solid var(--border);
}

h3 {
  font-size: 1.1rem;
  margin: 2rem 0 0.5rem;
}

h4 {
  font-size: 0.98rem;
  margin: 1.5rem 0 0.4rem;
}

p,
ul,
ol {
  margin: 0 0 1rem;
}

li + li {
  margin-top: 0.25rem;
}

blockquote {
  margin: 1.25rem 0;
  padding: 0.1rem 1.1rem;
  border-left: 3px solid var(--border);
  color: var(--fg-muted);
}

hr {
  height: 1px;
  border: 0;
  margin: 2.5rem 0;
  background: var(--border);
}

/* The opening paragraph of a page reads as a summary, with no need for the
 * author to mark it up as one. */
main > h1 + p {
  font-size: 1.1rem;
  color: var(--fg-muted);
  margin-bottom: 1.75rem;
}

/* ------------------------------------------------------------------ code */

code,
kbd,
samp {
  font-family: var(--mono);
  font-size: 0.87em;
}

:not(pre) > code {
  padding: 0.12em 0.36em;
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 5px;
  overflow-wrap: break-word;
}

pre {
  margin: 0 0 1.25rem;
  padding: 0.9rem 1.1rem;
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 8px;
  overflow-x: auto;
  line-height: 1.5;
}

pre code {
  background: none;
  border: 0;
  padding: 0;
  font-size: 0.85rem;
}

/* ---------------------------------------------------------------- tables */

/* The specification tables are wider than the measure; let them scroll
 * inside their own box rather than pushing the page sideways. */
table {
  display: block;
  width: fit-content;
  max-width: 100%;
  overflow-x: auto;
  margin: 0 0 1.25rem;
  border-collapse: collapse;
  font-size: 0.92rem;
}

th,
td {
  padding: 0.45rem 0.85rem;
  border: 1px solid var(--border);
  text-align: left;
  vertical-align: top;
}

th {
  background: var(--bg-sunken);
  font-weight: 600;
  white-space: nowrap;
}

td code {
  white-space: nowrap;
}

/* ------------------------------------------------------------- colophon */

.colophon {
  border-top: 1px solid var(--border);
  background: var(--bg-sunken);
  color: var(--fg-muted);
  font-size: 0.88rem;
}

.colophon p {
  max-width: 74rem;
  margin: 0 auto;
  padding: 1.25rem 1.5rem;
}

/* ------------------------------------------------------------ narrow */

@media (max-width: 52rem) {
  .shell {
    grid-template-columns: minmax(0, 1fr);
    gap: 0;
  }

  .sidebar {
    position: static;
    max-height: none;
    padding: 1.5rem 0 0.5rem;
    border-bottom: 1px solid var(--border);
  }

  main {
    padding-top: 1.75rem;
  }

  h1 {
    font-size: 1.75rem;
  }
}