:root {
  color-scheme: dark;
  --background: #071017;
  --surface: #0d1921;
  --surface-raised: #10212a;
  --text: #edf7f8;
  --muted: #8daac2;
  --faint: #698392;
  --line: #223742;
  --line-strong: #31505d;
  --accent: #4edce2;
  --accent-soft: #a9f3f4;
  --green: #69d9a1;
  --warning: #ffb548;
  --content-width: 76rem;
  --reading-width: 48rem;
  --gutter: clamp(1rem, 3vw, 2rem);
}

* { box-sizing: border-box; }

html {
  background: var(--background);
  scroll-behavior: smooth;
  scrollbar-gutter: stable;
}

body {
  margin: 0;
  min-width: 320px;
  background: var(--background);
  color: var(--text);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  font-size: 1rem;
  line-height: 1.6;
}

::selection {
  background: var(--accent);
  color: var(--background);
}

a {
  color: var(--accent);
  text-underline-offset: 0.2em;
}

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

button,
a { -webkit-tap-highlight-color: transparent; }

button { font: inherit; }

:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  top: 0.5rem;
  left: 0.5rem;
  z-index: 100;
  padding: 0.55rem 0.8rem;
  background: var(--accent);
  color: var(--background);
  transform: translateY(calc(-100% - 1rem));
}

.skip-link:focus { transform: translateY(0); }

.site-shell {
  display: flex;
  min-height: 100vh;
  flex-direction: column;
}

.site-header {
  border-bottom: 1px solid var(--line);
  background: var(--surface);
}

.header-inner {
  display: flex;
  width: min(100%, var(--content-width));
  min-height: 3.75rem;
  align-items: center;
  gap: 2rem;
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.brand {
  color: var(--text);
  font-family: Consolas, "Liberation Mono", monospace;
  font-size: 0.9rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-decoration: none;
}

.site-navigation {
  display: flex;
  flex: 1;
  align-items: center;
  justify-content: flex-end;
  gap: 2rem;
}

.navigation-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
}

.site-navigation a {
  color: var(--muted);
  font-size: 0.9rem;
  text-decoration: none;
}

.site-navigation a:hover,
.site-navigation a:focus-visible,
.site-navigation a[aria-current="page"] { color: var(--text); }

.workbench-link {
  padding: 0.45rem 0.7rem;
  border: 1px solid var(--line-strong);
  background: var(--surface-raised);
}

.workbench-link:hover,
.workbench-link:focus-visible { border-color: var(--accent); }

.section-tracker { display: none; }

.menu-toggle {
  display: none;
  margin-left: auto;
  padding: 0.35rem 0.6rem;
  border: 1px solid var(--line);
  background: transparent;
  color: var(--text);
}

.content-frame,
.footer-inner {
  width: min(100%, var(--content-width));
  margin-inline: auto;
  padding-inline: var(--gutter);
}

.content-frame {
  display: block;
  flex: 1;
}

.content-frame main { min-width: 0; }

.page { padding-block: clamp(2rem, 5vw, 4rem); }
.narrow-page { max-width: var(--reading-width); }
.page-heading { max-width: var(--reading-width); }

.home-page .page-heading > #page-title,
.learning-page > #page-title {
  margin-bottom: 1.5rem;
  padding-bottom: 2.5rem;
  border-bottom: 1px solid var(--line);
}

h1,
h2 {
  margin-top: 0;
  line-height: 1.2;
}

h1 {
  margin-bottom: 1rem;
  font-size: clamp(2rem, 4vw, 3rem);
}

h2 {
  margin-bottom: 0.65rem;
  font-size: clamp(1.25rem, 2vw, 1.55rem);
}

p,
li,
dd { color: var(--muted); }

.lead {
  margin: 0 0 1.25rem;
  color: var(--text);
  font-size: clamp(1.05rem, 1.8vw, 1.25rem);
}

.primary-link {
  display: inline-block;
  padding: 0.5rem 0.75rem;
  border: 1px solid var(--accent);
  background: var(--surface-raised);
  color: var(--text);
  text-decoration: none;
}

.workbench-preview figure { margin: 1rem 0 0; }

.workbench-preview img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
}

.workbench-preview figcaption {
  max-width: var(--reading-width);
  margin-top: 0.35rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.preview-disclaimer {
  margin: 0.65rem 0 0;
  color: var(--faint);
  font-size: 0.8rem;
}

.learning-modules {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1rem;
  margin-top: 2rem;
}

.learning-module {
  display: flex;
  min-width: 0;
  aspect-ratio: 1;
  flex-direction: column;
  justify-content: space-between;
  padding: clamp(1.25rem, 3vw, 1.75rem);
  border: 1px solid var(--line-strong);
  background: var(--surface);
  color: var(--text);
  text-decoration: none;
}

.learning-module h2 {
  margin: 0;
  color: var(--text);
}

.learning-module p {
  max-width: 18rem;
  margin: auto 0 0;
  color: var(--muted);
}

a.learning-module:hover,
a.learning-module:focus-visible {
  border-color: var(--accent);
  background: var(--surface-raised);
}

.learning-module--disabled {
  border-color: var(--line);
  opacity: 0.55;
}

.breadcrumbs {
  margin-bottom: 1.25rem;
  color: var(--faint);
  font-size: 0.85rem;
}

.breadcrumbs ol {
  display: flex;
  flex-wrap: wrap;
  gap: 0.35rem;
  margin: 0;
  padding: 0;
  list-style: none;
}

.breadcrumbs li {
  display: flex;
  align-items: center;
  gap: 0.35rem;
}

.breadcrumbs a { color: var(--muted); }
.breadcrumbs [aria-current="page"] { color: var(--text); }

.lesson-list {
  margin-top: 2.5rem;
  border-top: 1px solid var(--line-strong);
  border-bottom: 1px solid var(--line-strong);
}

.lesson-row {
  display: grid;
  grid-template-columns: 3.5rem minmax(0, 1fr);
  gap: 1rem;
  align-items: start;
  padding: 1.15rem 0.9rem;
  color: var(--text);
  text-decoration: none;
}

.lesson-row + .lesson-row { border-top: 1px solid var(--line); }

.lesson-row:hover,
.lesson-row:focus-visible { background: var(--surface); }

.lesson-row-number {
  color: var(--accent);
  font-family: Consolas, "Liberation Mono", monospace;
  font-size: 1.8rem;
}

.lesson-row-copy,
.lesson-row-copy strong,
.lesson-row-copy span { display: block; }

.lesson-row-copy strong {
  color: var(--text);
  font-size: 1.05rem;
}

.lesson-row-copy span {
  margin-top: 0.2rem;
  color: var(--muted);
}

.lesson-context {
  margin: 0 0 0.55rem;
  color: var(--accent);
  font-family: Consolas, "Liberation Mono", monospace;
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
}

.lesson-header { margin-bottom: 2.5rem; }

.lesson-page section[id] { scroll-margin-top: 5.75rem; }

.lesson-figure {
  width: 100%;
  margin: 1.5rem 0 0;
}

.lesson-figure--narrow {
  width: min(100%, 34rem);
  margin-right: auto;
}

.lesson-figure img,
.lesson-image-placeholder {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  border: 1px solid var(--line-strong);
  background: var(--surface);
}

.lesson-image-placeholder {
  display: grid;
  min-height: 15rem;
  place-items: center;
  padding: 2rem;
  color: var(--faint);
  text-align: center;
}

.lesson-figure figcaption {
  margin-top: 0.45rem;
  color: var(--faint);
  font-size: 0.85rem;
}

.lesson-callout {
  margin-top: 1.5rem;
  padding: 1rem 1.1rem;
  border-left: 2px solid var(--accent);
  background: var(--surface);
}

.lesson-callout--warning { border-left-color: var(--warning); }
.lesson-callout--example { border-left-color: var(--green); }

.lesson-callout h3 {
  margin: 0 0 0.35rem;
  color: var(--text);
  font-size: 1rem;
}

.lesson-callout p { margin: 0; }

.lesson-pagination {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 1.25rem;
  border-top: 1px solid var(--line-strong);
}

.lesson-pagination a,
.lesson-pagination span {
  color: var(--accent);
  text-decoration: none;
}

.lesson-pagination a:last-child,
.lesson-pagination span:last-child { text-align: right; }

.lesson-pagination [aria-disabled="true"] { color: var(--faint); }

.page section {
  margin-top: 2.5rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--line);
}

.narrow-page > section[id] { scroll-margin-top: 5.75rem; }

.page ul { padding-left: 1.25rem; }
.page li + li { margin-top: 0.45rem; }

.compatibility-list { margin: 1rem 0 0; }

.compatibility-list div {
  display: grid;
  grid-template-columns: minmax(12rem, 1fr) 2fr;
  gap: 1rem;
  padding-block: 0.75rem;
  border-top: 1px solid var(--line);
}

.compatibility-list div:last-child { border-bottom: 1px solid var(--line); }
.compatibility-list dt,
.compatibility-list dd { margin: 0; }

.compatibility-list dt {
  color: var(--text);
  font-weight: 650;
}

.compatibility-list div:first-child dt { color: var(--green); }

.compatibility-table {
  width: 100%;
  margin: 1rem 0 1.25rem;
  border-collapse: collapse;
  table-layout: fixed;
}

.compatibility-table th,
.compatibility-table td {
  padding: 0.75rem 0.85rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  text-align: left;
  vertical-align: top;
  overflow-wrap: anywhere;
}

.compatibility-table th {
  border-top-color: var(--line-strong);
  color: var(--text);
  font-weight: 650;
}

.compatibility-table th + th,
.compatibility-table td + td { border-left: 1px solid var(--line); }

.compatibility-table tbody tr:last-child td { border-bottom: 1px solid var(--line); }

.compatibility-table th:nth-child(1),
.compatibility-table td:nth-child(1) { width: 22%; }

.compatibility-table th:nth-child(2),
.compatibility-table td:nth-child(2) { width: 22%; }

.compatibility-table th:nth-child(3),
.compatibility-table td:nth-child(3) { width: 20%; }

.compatibility-table th:nth-child(4),
.compatibility-table td:nth-child(4) { width: 36%; }

.compatibility-table tbody td:last-child {
  color: var(--green);
  font-weight: 650;
}

.fine-print {
  color: var(--faint);
  font-size: 0.875rem;
}

.effective-date {
  color: var(--faint);
  font-size: 0.875rem;
}

code {
  font-family: Consolas, "Liberation Mono", monospace;
  font-size: 0.9em;
}

.not-found a { display: inline-block; margin-top: 0.5rem; }

.back-link {
  display: block;
  margin-top: 0.5rem;
  padding: 0;
  border: 0;
  background: transparent;
  color: var(--accent);
  cursor: pointer;
  text-decoration: underline;
  text-underline-offset: 0.2em;
}

.back-link:hover { text-decoration-thickness: 2px; }

.site-footer {
  padding-block: 1rem;
  border-top: 1px solid var(--line);
  background: var(--surface);
  color: var(--faint);
}

.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem 2rem;
}

.footer-navigation {
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem 1rem;
}

.footer-navigation a {
  color: var(--muted);
  font-size: 0.8rem;
  text-decoration: none;
}

.footer-navigation a:hover,
.footer-navigation a:focus-visible,
.footer-navigation a[aria-current="page"] { color: var(--text); }

.ad-rail,
.ad-rail[hidden],
.ad-primary-stage[hidden],
.ad-placement[hidden] { display: none; }

.ad-rail {
  width: 300px;
  min-width: 0;
  align-self: stretch;
  flex-direction: column;
  padding-top: clamp(2rem, 5vw, 4rem);
}

.ad-primary-stage {
  min-height: 600px;
  flex: 1 1 auto;
}

.ad-placement[data-ad-slot="right-rail-primary"] {
  position: sticky;
  top: 2rem;
  width: 300px;
  height: 600px;
  overflow: hidden;
}

.ad-primary-stage:not([hidden]) + .ad-placement:not([hidden]) { margin-top: 2rem; }

@media (min-width: 120rem) {
  .content-frame:has(.ad-rail:not([hidden])) {
    display: grid;
    width: calc(var(--content-width) + 300px + 2rem);
    grid-template-columns: minmax(0, calc(var(--content-width) - var(--gutter) - var(--gutter))) 300px;
    gap: 2rem;
    margin-right: 0;
    margin-left: calc(50% - 38rem);
  }

  .ad-rail:not([hidden]) { display: flex; }
}

@media (min-width: 100rem) {
  .section-tracker {
    position: fixed;
    top: 5.5rem;
    left: calc(50vw - 48rem);
    z-index: 10;
    display: flex;
    width: 8.5rem;
    flex-direction: column;
    border-left: 1px solid var(--line);
  }

  .section-tracker a {
    margin-left: -1px;
    padding: 0.4rem 0 0.4rem 0.75rem;
    border-left: 1px solid transparent;
    color: var(--faint);
    font-size: 0.8rem;
    line-height: 1.35;
    text-decoration: none;
  }

  .section-tracker a:hover,
  .section-tracker a:focus-visible { color: var(--text); }

  .section-tracker a[aria-current="location"] {
    border-left: 2px solid var(--accent);
    color: var(--accent);
  }
}

@media (max-width: 720px) {
  .header-inner { min-height: 3.5rem; }
  .menu-toggle { display: block; }

  .site-navigation {
    position: absolute;
    top: 3.5rem;
    right: 0;
    left: 0;
    z-index: 20;
    display: none;
    align-items: stretch;
    padding: 1rem var(--gutter) 1.25rem;
    border-bottom: 1px solid var(--line);
    background: var(--background);
  }

  .menu-open { overflow: hidden; }
  .menu-open .site-navigation { display: block; }

  .navigation-links {
    display: grid;
    gap: 0;
  }

  .site-navigation a {
    display: block;
    padding-block: 0.65rem;
  }

  .workbench-link {
    margin-top: 0.5rem;
    padding-inline: 0;
    border: 0;
    border-top: 1px solid var(--line);
  }

  .workbench-entry,
  .site-navigation .workbench-entry { display: none; }

  .compatibility-list div {
    grid-template-columns: 1fr;
    gap: 0.2rem;
  }

  .compatibility-table th,
  .compatibility-table td {
    padding: 0.6rem 0.5rem;
    font-size: 0.85rem;
  }

  .learning-modules { grid-template-columns: 1fr; }

  .learning-module {
    min-height: 11rem;
    aspect-ratio: auto;
  }

  .lesson-row {
    grid-template-columns: 2.25rem minmax(0, 1fr);
    gap: 0.75rem;
    padding-inline: 0.5rem;
  }

  .lesson-image-placeholder { min-height: 10rem; }

  .lesson-pagination {
    grid-template-columns: 1fr;
    gap: 0.65rem;
  }

  .lesson-pagination a:last-child,
  .lesson-pagination span:last-child { text-align: left; }

  .footer-inner { align-items: flex-start; }

  .footer-navigation {
    justify-content: flex-end;
    text-align: right;
  }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}