/*
 * The whole of this site's styling. One stylesheet, no framework, no build step: the site is Markdown
 * poured into _layouts/default.html, and this is what makes it readable.
 *
 * Both color schemes are declared as custom properties and switched by prefers-color-scheme, so the page a
 * reader gets is the one their system asked for and neither scheme is an afterthought.
 */

:root {
  color-scheme: light dark;

  --page: #ffffff;
  --sunken: #f4f6f8;
  --ink: #1c2024;
  --ink-soft: #4b5563;
  --rule: #dfe3e8;
  --accent: #006c85;
  --accent-soft: #e3f1f5;
  --code-ink: #22303a;

  --measure: 46rem;
  --sans: system-ui, -apple-system, "Segoe UI", Roboto, "Helvetica Neue", Arial, sans-serif;
  --mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --page: #11161a;
    --sunken: #1a2127;
    --ink: #e7ecf0;
    --ink-soft: #a8b3bd;
    --rule: #2b343c;
    --accent: #67cde3;
    --accent-soft: #17313a;
    --code-ink: #dbe4ea;
  }
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  background: var(--page);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 1rem;
  line-height: 1.65;
  -webkit-text-size-adjust: 100%;
}

a {
  color: var(--accent);
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
}

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

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

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

.skip:focus {
  left: 1rem;
  top: 1rem;
  z-index: 2;
  padding: 0.5rem 0.75rem;
  background: var(--page);
  border: 1px solid var(--rule);
  border-radius: 6px;
}

/* ---- the banner ---- */

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

.banner-inner {
  max-width: 72rem;
  margin: 0 auto;
  padding: 1.5rem 1.25rem 1.25rem;
}

.wordmark {
  font-size: 1.4rem;
  font-weight: 650;
  letter-spacing: -0.01em;
  color: var(--ink);
  text-decoration: none;
}

.tagline {
  margin: 0.15rem 0 0.6rem;
  color: var(--ink-soft);
}

.elsewhere {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1rem;
  margin: 0;
  font-size: 0.9rem;
}

/* ---- the two columns ---- */

.page {
  max-width: 72rem;
  margin: 0 auto;
  padding: 0 1.25rem 3rem;
  display: grid;
  grid-template-columns: 1fr;
  gap: 0 2.5rem;
}

@media (min-width: 60rem) {
  .page {
    grid-template-columns: 14rem minmax(0, 1fr);
  }

  .chapters {
    position: sticky;
    top: 0;
    align-self: start;
    max-height: 100vh;
    overflow-y: auto;
    padding-top: 2rem;
  }
}

.chapters ol {
  list-style: none;
  margin: 1.5rem 0 0;
  padding: 0;
  font-size: 0.94rem;
}

.chapters li {
  margin: 0;
  border-left: 2px solid var(--rule);
}

.chapters a {
  display: block;
  padding: 0.35rem 0.75rem;
  color: var(--ink-soft);
  text-decoration: none;
}

.chapters a:hover {
  color: var(--accent);
}

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

/* ---- the prose ---- */

.prose {
  max-width: var(--measure);
  padding-top: 1.5rem;
}

.prose h1,
.prose h2,
.prose h3 {
  line-height: 1.25;
  letter-spacing: -0.01em;
}

.prose h1 {
  font-size: 2rem;
  margin: 0.75rem 0 1rem;
}

.prose h2 {
  font-size: 1.4rem;
  margin: 2.5rem 0 0.75rem;
  padding-top: 0.75rem;
  border-top: 1px solid var(--rule);
}

.prose h3 {
  font-size: 1.1rem;
  margin: 1.75rem 0 0.5rem;
}

.prose blockquote {
  margin: 1.25rem 0;
  padding: 0.1rem 1rem;
  border-left: 3px solid var(--accent);
  color: var(--ink-soft);
}

.prose table {
  width: 100%;
  margin: 1.25rem 0;
  border-collapse: collapse;
  font-size: 0.94rem;
}

.prose th,
.prose td {
  padding: 0.45rem 0.6rem;
  border-bottom: 1px solid var(--rule);
  text-align: left;
  vertical-align: top;
}

.prose th {
  font-size: 0.82rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--ink-soft);
}

.prose code {
  font-family: var(--mono);
  font-size: 0.88em;
  padding: 0.1em 0.3em;
  border-radius: 4px;
  background: var(--sunken);
  color: var(--code-ink);
}

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

.prose pre code {
  padding: 0;
  background: none;
  font-size: 0.86rem;
}

.prose hr {
  margin: 2.5rem 0;
  border: 0;
  border-top: 1px solid var(--rule);
}

.prose li {
  margin: 0.35rem 0;
}

/* ---- Rouge, the highlighter GitHub Pages ships with ---- */

.highlight .c,
.highlight .c1,
.highlight .cm,
.highlight .cs {
  color: var(--ink-soft);
  font-style: italic;
}

.highlight .k,
.highlight .kd,
.highlight .kn,
.highlight .kp,
.highlight .kr,
.highlight .kt {
  color: var(--accent);
}

.highlight .s,
.highlight .s1,
.highlight .s2,
.highlight .sb,
.highlight .se {
  color: #a4432b;
}

.highlight .nf,
.highlight .nx {
  font-weight: 600;
}

.highlight .m,
.highlight .mi,
.highlight .mf {
  color: #7a4bab;
}

@media (prefers-color-scheme: dark) {
  .highlight .s,
  .highlight .s1,
  .highlight .s2,
  .highlight .sb,
  .highlight .se {
    color: #e8a58c;
  }

  .highlight .m,
  .highlight .mi,
  .highlight .mf {
    color: #c9a6ee;
  }
}

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

.colophon {
  border-top: 1px solid var(--rule);
  background: var(--sunken);
  color: var(--ink-soft);
  font-size: 0.9rem;
}

.colophon p {
  max-width: 72rem;
  margin: 0 auto;
  padding: 0.6rem 1.25rem;
}

.colophon p:first-child {
  padding-top: 1.25rem;
}

.colophon p:last-child {
  padding-bottom: 1.5rem;
}