:root {
  --paper: #f5f5f0;
  --panel: #fcfcf9;
  --wash: #eef0e7;
  --line: #d9dbd0;
  --line-soft: #e6e8de;
  --line-strong: #c2c8b9;
  --ink: #1b3238;
  --ink-soft: #47605b;
  --ink-faint: #5f736d;
  --board: #092a30;
  --board-raise: #10353d;
  --board-deep: #06232a;
  --chalk: #dcebe6;
  --chalk-soft: #9db8b0;
  --blue: #5371ff;
  --blue-deep: #3f55e6;
  --blue-text: #3346d3;
  --blue-wash: #e9edff;
  --green: #2f7a58;
  --green-wash: #e4f2ea;
  --amber: #9a6a1f;
  --red: #b4574a;
  --red-wash: #f7e9e6;
  --tok-kw: #9fadff;
  --tok-str: #ecc989;
  --tok-num: #97dfc0;
  --tok-comment: #6f9187;
  --tok-fn: #86d7e8;
  --tok-type: #86d7e8;
  --tok-builtin: #c7b3ff;
  --tok-meta: #f0a8a0;
  --mono: ui-monospace, "Cascadia Code", "Cascadia Mono", Consolas, "SF Mono", Menlo, "DejaVu Sans Mono", monospace;
  --serif: Charter, "Iowan Old Style", "Palatino Linotype", Palatino, Georgia, serif;
  --wide: 68rem;
  --shadow-print: 6px 6px 0 rgba(10, 57, 63, 0.08);
}

* {
  box-sizing: border-box;
}

[hidden] {
  display: none !important;
}

html {
  overflow-x: clip;
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--mono);
  font-size: 16px;
  line-height: 1.6;
  overflow-x: clip;
}

::selection {
  background: #ccd6ff;
}

:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 2px;
  border-radius: 2px;
}

img {
  max-width: 100%;
}

a {
  color: var(--blue-text);
}

button {
  font: inherit;
}

.skip-link {
  position: absolute;
  left: -100vw;
  top: 0;
  background: var(--board);
  color: var(--chalk);
  padding: 0.6rem 1rem;
  z-index: 100;
}

.skip-link:focus {
  left: 0;
}

.site-head {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 0.65rem 1.25rem;
  background: var(--paper);
  border-bottom: 1px solid var(--line);
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  text-decoration: none;
}

.brand img {
  display: block;
}

.brand-name {
  font-size: 0.7rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--ink);
  line-height: 1.35;
  max-width: 10rem;
}

.site-nav a {
  font-size: 0.78rem;
  color: var(--ink-soft);
  text-decoration: none;
  margin-left: 1.4rem;
}

.site-nav a:hover {
  color: var(--ink);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.site-nav a[aria-current] {
  color: var(--ink);
  font-weight: 700;
}

main {
  display: block;
  width: 100%;
  max-width: var(--wide);
  margin-inline: auto;
  padding-inline: 1.25rem;
  min-height: 60vh;
}

main:focus {
  outline: none;
}

h1,
h2,
h3,
h4 {
  font-family: var(--mono);
  line-height: 1.2;
  margin: 0;
}

.eyebrow {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.16em;
  color: var(--ink-faint);
  margin: 0 0 1rem;
}

.eyebrow a {
  color: inherit;
}

.btn {
  display: inline-block;
  font-family: var(--mono);
  font-size: 0.8rem;
  font-weight: 600;
  padding: 0.65em 1.15em;
  border-radius: 6px;
  border: 1px solid transparent;
  background: var(--blue-deep);
  color: #fff;
  text-decoration: none;
  cursor: pointer;
}

.btn:hover {
  background: var(--blue-text);
}

.btn:disabled {
  opacity: 0.55;
  cursor: wait;
}

.btn-ghost {
  background: transparent;
  border-color: var(--line-strong);
  color: var(--ink);
}

.btn-ghost:hover {
  background: var(--wash);
  border-color: var(--ink-soft);
}

.btn-chalk {
  background: var(--chalk);
  color: var(--board);
}

.btn-chalk:hover {
  background: #fff;
}

.btn-ghost-chalk {
  background: transparent;
  border-color: rgba(220, 235, 230, 0.4);
  color: var(--chalk);
}

.btn-ghost-chalk:hover {
  border-color: var(--chalk);
  background: rgba(220, 235, 230, 0.08);
}

.chip {
  display: inline-block;
  font-size: 0.62rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  padding: 0.1em 0.6em;
  border-radius: 99px;
  border: 1px solid var(--line-strong);
  color: var(--ink-faint);
}

.chip-open {
  background: var(--blue-wash);
  border-color: transparent;
  color: var(--blue-text);
}

.chip-next {
  background: var(--blue-deep);
  border-color: transparent;
  color: #fff;
}

.bar {
  height: 4px;
  border-radius: 99px;
  background: var(--line-soft);
  overflow: hidden;
}

.bar span {
  display: block;
  height: 100%;
  background: var(--blue-deep);
  border-radius: 99px;
}

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 0.95fr);
  gap: 3.5rem;
  align-items: center;
  padding-block: 4.5rem 3.5rem;
}

.hero h1 {
  font-size: clamp(1.9rem, 4vw, 2.7rem);
  letter-spacing: -0.02em;
  margin: 0 0 1.2rem;
}

.hero-lede {
  font-family: var(--serif);
  font-size: 1.15rem;
  line-height: 1.7;
  color: var(--ink-soft);
  margin: 0 0 1.8rem;
  max-width: 34em;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin: 0;
}

.term {
  background: var(--board);
  border-radius: 10px;
  box-shadow: var(--shadow-print);
  overflow: hidden;
}

.term-bar {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.3rem 1rem;
  padding: 0.6rem 1rem;
  font-size: 0.72rem;
  color: var(--chalk);
  border-bottom: 1px solid rgba(220, 235, 230, 0.12);
}

.term-hint {
  color: var(--chalk-soft);
  font-size: 0.68rem;
}

.term-src {
  display: block;
  width: 100%;
  border: 0;
  resize: vertical;
  background: transparent;
  color: var(--chalk);
  font-family: var(--mono);
  font-size: 0.85rem;
  line-height: 1.6;
  padding: 0.85rem 1rem;
}

.term-src:focus-visible {
  outline-offset: -2px;
}

.term-foot {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem 0.9rem;
  padding: 0.35rem 1rem 0.85rem;
}

.btn-run {
  background: var(--blue);
}

.btn-run:hover {
  background: #6b84ff;
}

.term-note {
  font-size: 0.68rem;
  color: var(--chalk-soft);
}

.term-out {
  margin: 0;
  padding: 0.7rem 1rem;
  border-top: 1px solid rgba(220, 235, 230, 0.12);
  background: var(--board-deep);
  font-size: 0.8rem;
  line-height: 1.6;
  white-space: pre-wrap;
  word-break: break-word;
}

.out-line {
  color: var(--chalk);
  white-space: pre-wrap;
  word-break: break-word;
}

.out-line.out-error {
  color: #ff9d8f;
}

.out-line.out-warn {
  color: var(--tok-str);
}

.out-line.out-quiet {
  color: var(--chalk-soft);
  font-style: italic;
}

.resume {
  display: flex;
  flex-direction: column;
  gap: 0.3rem;
  margin-block: 0 2.5rem;
  padding: 1rem 1.25rem;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 8px;
  text-decoration: none;
  color: var(--ink);
}

.resume:hover {
  border-color: var(--blue);
}

.resume-label {
  font-size: 0.65rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--blue-text);
}

.resume-title {
  font-size: 0.9rem;
}

.strip {
  border-top: 1px solid var(--line);
  padding-block: 3rem;
}

.strip-head {
  display: grid;
  grid-template-columns: 16rem minmax(0, 1fr);
  gap: 2rem;
  margin-bottom: 2rem;
}

.strip-head h2 {
  font-size: 1.3rem;
  letter-spacing: -0.01em;
}

.strip-head p {
  font-family: var(--serif);
  color: var(--ink-soft);
  margin: 0;
  max-width: 38em;
}

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

.course-row {
  display: grid;
  grid-template-columns: 9rem minmax(0, 1fr) auto auto;
  gap: 1.5rem;
  align-items: center;
  padding: 1.1rem 0.5rem;
  border-top: 1px solid var(--line-soft);
  text-decoration: none;
  color: var(--ink);
}

.course-rows li:first-child .course-row {
  border-top: 0;
}

.course-row:hover {
  background: var(--panel);
}

.course-row-name {
  font-size: 1.05rem;
  font-weight: 700;
}

.course-row:hover .course-row-name {
  text-decoration: underline;
  text-decoration-color: var(--blue);
  text-underline-offset: 4px;
}

.course-row-tag {
  font-family: var(--serif);
  color: var(--ink-soft);
  font-size: 0.95rem;
}

.course-row-meta {
  font-size: 0.72rem;
  color: var(--ink-faint);
  white-space: nowrap;
}

.course-row-progress {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.72rem;
  color: var(--blue-text);
}

.course-row-progress .bar {
  width: 6rem;
}

.cat-index {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: 1fr 1fr;
  column-gap: 3rem;
}

.cat-index a {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.2rem 1rem;
  padding: 0.8rem 0.25rem;
  border-top: 1px solid var(--line-soft);
  font-size: 0.85rem;
  color: var(--ink);
  text-decoration: none;
}

.cat-index a:hover {
  background: var(--panel);
  color: var(--blue-text);
}

.cat-count {
  font-size: 0.7rem;
  color: var(--ink-faint);
  white-space: nowrap;
}

.steps {
  list-style: none;
  counter-reset: step;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 2.5rem;
}

.steps li {
  counter-increment: step;
}

.steps h3 {
  font-size: 0.95rem;
  margin-bottom: 0.6rem;
}

.steps h3::before {
  content: counter(step) ". ";
  color: var(--blue-text);
}

.steps p {
  font-family: var(--serif);
  color: var(--ink-soft);
  margin: 0;
  font-size: 0.98rem;
}

.contribute {
  margin-top: 3rem;
  margin-inline: calc(50% - 50vw);
  padding-inline: calc(50vw - 50%);
  background: var(--board);
}

.contribute-inner {
  max-width: var(--wide);
  margin-inline: auto;
  padding: 3.5rem 1.25rem;
}

.contribute h2 {
  color: var(--chalk);
  font-size: 1.6rem;
  margin-bottom: 1rem;
}

.contribute p {
  font-family: var(--serif);
  color: var(--chalk-soft);
  max-width: 40em;
  margin: 0 0 1.6rem;
}

.page-head {
  padding-block: 3rem 1.5rem;
}

.page-head h1 {
  font-size: clamp(1.7rem, 3.5vw, 2.4rem);
  letter-spacing: -0.02em;
  margin-bottom: 1rem;
}

.page-lede {
  font-family: var(--serif);
  font-size: 1.05rem;
  color: var(--ink-soft);
  max-width: 42em;
  margin: 0;
}

.catalog-search {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  flex-wrap: wrap;
  margin: 1.8rem 0 0;
}

.catalog-search input {
  font-family: var(--mono);
  font-size: 0.85rem;
  padding: 0.55em 0.85em;
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  background: var(--panel);
  color: var(--ink);
  width: min(26rem, 100%);
}

.catalog-search input:focus {
  border-color: var(--blue);
}

.catalog-count {
  font-size: 0.72rem;
  color: var(--ink-faint);
}

.lang-group h2 {
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.14em;
  color: var(--ink-faint);
  margin: 2.5rem 0 0;
  padding-bottom: 0.5rem;
}

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

.lang-row-link {
  display: grid;
  grid-template-columns: 10rem minmax(0, 1fr) auto;
  gap: 1.25rem;
  align-items: baseline;
  padding: 0.85rem 0.4rem;
  border-top: 1px solid var(--line-soft);
  text-decoration: none;
  color: var(--ink);
}

.lang-row-link:hover {
  background: var(--panel);
}

.lang-name {
  font-size: 0.95rem;
  font-weight: 700;
}

.lang-row-link:hover .lang-name {
  color: var(--blue-text);
}

.lang-tagline {
  font-family: var(--serif);
  font-size: 0.95rem;
  color: var(--ink-soft);
}

.lang-meta {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  font-size: 0.72rem;
  color: var(--ink-faint);
  white-space: nowrap;
}

.lang-done {
  color: var(--blue-text);
}

.catalog-empty {
  font-family: var(--serif);
  color: var(--ink-soft);
  padding: 2rem 0.25rem;
  border-top: 1px solid var(--line-soft);
}

.course-head {
  padding-bottom: 2rem;
}

.course-tagline {
  font-family: var(--serif);
  font-size: 1.1rem;
  color: var(--ink-soft);
  margin: 0 0 1rem;
}

.course-blurb {
  font-family: var(--serif);
  font-size: 1.02rem;
  line-height: 1.75;
  color: var(--ink-soft);
  max-width: 46em;
  margin: 0 0 1.2rem;
}

.course-meta {
  font-size: 0.75rem;
  color: var(--ink-faint);
  margin: 0 0 1.6rem;
}

.course-progress {
  display: flex;
  align-items: center;
  gap: 0.9rem;
  margin-top: 1.4rem;
  font-size: 0.75rem;
  color: var(--ink-soft);
}

.course-progress .bar {
  width: 11rem;
}

.link-quiet {
  background: none;
  border: 0;
  padding: 0;
  font-size: 0.72rem;
  color: var(--ink-faint);
  text-decoration: underline;
  text-underline-offset: 3px;
  cursor: pointer;
}

.link-quiet:hover {
  color: var(--red);
}

.outline-note {
  border: 1px dashed var(--line-strong);
  border-radius: 8px;
  background: var(--panel);
  padding: 1.1rem 1.4rem;
  margin-bottom: 1.5rem;
}

.outline-note p {
  font-family: var(--serif);
  color: var(--ink-soft);
  margin: 0.4rem 0 0;
  max-width: 52em;
}

.callout-label {
  font-family: var(--mono);
  font-size: 0.66rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  margin: 0;
  color: var(--blue-text);
}

.modules {
  list-style: none;
  margin: 0 0 4rem;
  padding: 0;
}

.module {
  border-top: 1px solid var(--line);
  padding-block: 2.2rem;
}

.module-head {
  display: flex;
  gap: 1.4rem;
  align-items: baseline;
}

.module-no {
  font-size: 1.9rem;
  font-weight: 700;
  color: var(--line-strong);
  min-width: 2.9rem;
  line-height: 1;
}

.module-head h2 {
  font-size: 1.15rem;
}

.module-head p {
  font-family: var(--serif);
  color: var(--ink-soft);
  margin: 0.4rem 0 0;
  max-width: 46em;
  font-size: 0.98rem;
}

.lessons {
  list-style: none;
  margin: 1.2rem 0 0;
  padding: 0 0 0 4.3rem;
}

.lesson-item a,
.lesson-item.is-dead {
  display: flex;
  align-items: center;
  gap: 0.8rem;
  padding: 0.5rem 0.6rem;
  border-radius: 6px;
  font-size: 0.875rem;
  text-decoration: none;
  color: var(--ink);
}

.lesson-item a:hover {
  background: var(--panel);
}

.lesson-item a:hover .lesson-title {
  text-decoration: underline;
  text-underline-offset: 3px;
}

.lesson-state {
  flex: none;
  width: 1.15rem;
  height: 1.15rem;
  border: 1px solid var(--line-strong);
  border-radius: 4px;
  font-size: 0.7rem;
  line-height: 1.05rem;
  text-align: center;
  color: #fff;
  background: var(--panel);
}

.is-done .lesson-state {
  background: var(--blue-deep);
  border-color: var(--blue-deep);
}

.is-next > a {
  background: var(--blue-wash);
}

.lesson-item.is-dead {
  color: var(--ink-soft);
}

.lesson-min {
  margin-left: auto;
  font-size: 0.68rem;
  color: var(--ink-faint);
  white-space: nowrap;
}

.lesson-layout {
  display: grid;
  grid-template-columns: 15rem minmax(0, 1fr);
  gap: 3.5rem;
  padding-top: 2rem;
}

.lesson-side {
  position: sticky;
  top: 4.2rem;
  align-self: start;
  max-height: calc(100vh - 5.5rem);
  overflow-y: auto;
  padding-bottom: 2rem;
}

.side-course {
  margin: 0 0 0.4rem;
}

.side-course a {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--ink);
  text-decoration: none;
}

.side-course a:hover {
  color: var(--blue-text);
}

.side-progress {
  font-size: 0.7rem;
  color: var(--ink-faint);
  margin: 0 0 0.5rem;
}

.side-outline {
  margin-top: 1.4rem;
}

.side-outline details {
  border-top: 1px solid var(--line-soft);
}

.side-outline summary {
  list-style: none;
  cursor: pointer;
  font-size: 0.78rem;
  font-weight: 600;
  padding: 0.6rem 0.2rem;
  color: var(--ink-soft);
  display: flex;
  justify-content: space-between;
  gap: 0.5rem;
}

.side-outline summary::-webkit-details-marker {
  display: none;
}

.side-outline summary::after {
  content: "+";
  color: var(--ink-faint);
}

.side-outline details[open] summary::after {
  content: "−";
}

.side-outline ol {
  list-style: none;
  margin: 0 0 0.8rem;
  padding: 0;
}

.side-outline li a {
  display: flex;
  gap: 0.5rem;
  align-items: baseline;
  padding: 0.28rem 0.2rem 0.28rem 0.9rem;
  border-left: 2px solid transparent;
  font-size: 0.76rem;
  color: var(--ink-soft);
  text-decoration: none;
}

.side-outline li a:hover {
  color: var(--ink);
  background: var(--panel);
}

.side-outline li.is-current a {
  border-left-color: var(--blue-deep);
  color: var(--ink);
  font-weight: 600;
}

.side-done {
  margin-left: auto;
  color: var(--blue-text);
  font-size: 0.68rem;
}

.lesson-head {
  border-bottom: 1px solid var(--line);
  padding-bottom: 1.5rem;
  margin-bottom: 1.8rem;
}

.lesson-head h1 {
  font-size: clamp(1.5rem, 3vw, 2rem);
  letter-spacing: -0.015em;
  margin-bottom: 0.8rem;
}

.lesson-meta {
  font-size: 0.72rem;
  color: var(--ink-faint);
  margin: 0;
}

.prose {
  font-family: var(--serif);
  font-size: 1.0625rem;
  line-height: 1.75;
  max-width: 44rem;
}

.prose p {
  margin: 0.9em 0;
}

.prose h2 {
  font-size: 1.25rem;
  margin: 2.2em 0 0.7em;
  padding-top: 1.4em;
  border-top: 1px solid var(--line-soft);
}

.prose h3 {
  font-size: 1rem;
  margin: 1.8em 0 0.5em;
}

.prose ul,
.prose ol {
  margin: 0.9em 0;
  padding-left: 1.4em;
}

.prose li {
  margin: 0.35em 0;
}

.prose li ul {
  margin: 0.35em 0;
}

.prose code {
  font-family: var(--mono);
  font-size: 0.85em;
  background: #e9ece1;
  border-radius: 4px;
  padding: 0.1em 0.35em;
}

.prose pre code {
  background: none;
  border-radius: 0;
  padding: 0;
}

.prose blockquote {
  margin: 1.4em 0;
  padding: 0.2em 0 0.2em 1.2em;
  border-left: 3px solid var(--line-strong);
  color: var(--ink-soft);
  font-style: italic;
}

.prose blockquote p {
  margin: 0.4em 0;
}

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

.prose img {
  border-radius: 6px;
}

.table-scroll {
  overflow-x: auto;
  margin: 1.4em 0;
}

.prose table {
  border-collapse: collapse;
  font-family: var(--mono);
  font-size: 0.8rem;
  min-width: 60%;
}

.prose th,
.prose td {
  border: 1px solid var(--line);
  padding: 0.5em 0.8em;
  text-align: left;
  vertical-align: top;
}

.prose th {
  background: var(--panel);
  font-weight: 600;
}

.callout {
  margin: 1.6em 0;
  padding: 1em 1.25em;
  border: 1px solid var(--line);
  border-left: 3px solid var(--blue-deep);
  border-radius: 8px;
  background: var(--panel);
  font-size: 0.98rem;
}

.callout p {
  margin: 0.45em 0 0;
}

.callout-tip {
  border-left-color: var(--green);
}

.callout-tip .callout-label {
  color: var(--green);
}

.callout-warn {
  border-left-color: var(--amber);
}

.callout-warn .callout-label {
  color: var(--amber);
}

.callout-deep {
  background: var(--board-raise);
  border-color: var(--board-raise);
  color: var(--chalk);
}

.callout-deep .callout-label {
  color: var(--tok-fn);
}

.callout-deep code {
  background: rgba(220, 235, 230, 0.14);
  color: var(--chalk);
}

.callout-deep a {
  color: var(--tok-kw);
}

.code {
  margin: 1.6em 0;
  border-radius: 10px;
  overflow: hidden;
  background: var(--board);
  box-shadow: var(--shadow-print);
}

.code figcaption {
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 1rem;
  padding: 0.4rem 0.5rem 0.4rem 1rem;
  background: var(--board-raise);
  font-family: var(--mono);
  font-size: 0.68rem;
  color: var(--chalk-soft);
}

.code-lang {
  letter-spacing: 0.08em;
}

.code-acts {
  display: flex;
  gap: 0.4rem;
}

.code-act {
  font-family: var(--mono);
  font-size: 0.66rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--chalk-soft);
  background: transparent;
  border: 1px solid rgba(220, 235, 230, 0.2);
  border-radius: 5px;
  padding: 0.3em 0.75em;
  cursor: pointer;
  text-decoration: none;
}

.code-act:hover {
  color: var(--chalk);
  border-color: var(--chalk-soft);
}

.code-act-run {
  background: var(--blue);
  border-color: transparent;
  color: #fff;
}

.code-act-run:hover {
  background: #6b84ff;
  color: #fff;
}

.code pre {
  margin: 0;
  padding: 1rem 1.1rem;
  overflow-x: auto;
}

.code pre code {
  font-family: var(--mono);
  font-size: 0.85rem;
  line-height: 1.65;
  color: var(--chalk);
  tab-size: 4;
}

.code-src {
  display: block;
  width: 100%;
  border: 0;
  background: var(--board);
  color: var(--chalk);
  font-family: var(--mono);
  font-size: 0.85rem;
  line-height: 1.65;
  padding: 1rem 1.1rem;
  resize: vertical;
}

.code-src:focus-visible {
  outline-offset: -2px;
}

.code-out {
  border-top: 1px solid rgba(220, 235, 230, 0.12);
  background: var(--board-deep);
  padding: 0.7rem 1.1rem;
  font-family: var(--mono);
  font-size: 0.8rem;
  line-height: 1.6;
}

.code-output {
  background: var(--wash);
  border: 1px solid var(--line);
  box-shadow: none;
}

.code-output figcaption {
  background: transparent;
  border-bottom: 1px solid var(--line);
  color: var(--ink-faint);
}

.code-output pre code {
  color: var(--ink-soft);
}

.tok-kw {
  color: var(--tok-kw);
}

.tok-str {
  color: var(--tok-str);
}

.tok-num {
  color: var(--tok-num);
}

.tok-comment {
  color: var(--tok-comment);
  font-style: italic;
}

.tok-fn {
  color: var(--tok-fn);
}

.tok-type {
  color: var(--tok-type);
}

.tok-builtin {
  color: var(--tok-builtin);
}

.tok-meta {
  color: var(--tok-meta);
}

.quiz {
  margin: 2em 0;
  padding: 1.2rem 1.4rem;
  border: 1px solid var(--line);
  border-top: 3px solid var(--blue-deep);
  border-radius: 10px;
  background: var(--panel);
}

.quiz-q {
  font-size: 1.02rem;
  margin: 0.5em 0 1em;
}

.quiz-opts {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 0.5rem;
}

.quiz-opt {
  width: 100%;
  text-align: left;
  font-family: var(--mono);
  font-size: 0.84rem;
  padding: 0.6em 0.9em;
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  background: var(--paper);
  color: var(--ink);
  cursor: pointer;
}

.quiz-opt:hover:not(:disabled) {
  border-color: var(--blue);
  background: var(--blue-wash);
}

.quiz-opt:disabled {
  cursor: default;
}

.quiz-opt.is-right {
  border-color: var(--green);
  background: var(--green-wash);
}

.quiz-opt.is-wrong {
  border-color: var(--red);
  background: var(--red-wash);
  opacity: 0.75;
}

.quiz-result {
  font-family: var(--mono);
  font-size: 0.78rem;
  font-weight: 600;
  margin: 0.9em 0 0;
}

.quiz-explain {
  font-size: 0.95rem;
  color: var(--ink-soft);
  border-top: 1px solid var(--line-soft);
  padding-top: 0.9em;
  margin: 0.9em 0 0;
}

.quiz-broken p {
  font-family: var(--serif);
  color: var(--red);
  margin: 0.4em 0 0;
}

.lesson-nav {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  gap: 1.25rem;
  align-items: center;
  border-top: 1px solid var(--line);
  margin-top: 3.5rem;
  padding-block: 1.6rem 3rem;
}

.lesson-step {
  display: flex;
  flex-direction: column;
  gap: 0.15rem;
  font-family: var(--mono);
  font-size: 0.78rem;
  color: var(--ink-soft);
  text-decoration: none;
}

.lesson-step span {
  font-size: 0.62rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.12em;
  color: var(--ink-faint);
}

.lesson-step:hover {
  color: var(--blue-text);
}

.lesson-step.is-forward {
  text-align: right;
  justify-self: end;
}

.lesson-step.is-empty {
  visibility: hidden;
}

.site-foot {
  border-top: 1px solid var(--line);
  margin-top: 4rem;
  background: var(--panel);
}

.foot-inner {
  max-width: var(--wide);
  margin-inline: auto;
  padding: 2.5rem 1.25rem;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 3rem;
}

.foot-brand {
  display: flex;
  gap: 0.9rem;
  align-items: flex-start;
}

.foot-brand img {
  margin-top: 0.2rem;
}

.foot-brand p {
  font-family: var(--serif);
  font-size: 0.92rem;
  color: var(--ink-soft);
  max-width: 30em;
  margin: 0;
}

.foot-nav {
  display: flex;
  flex-direction: column;
  gap: 0.55rem;
}

.foot-nav a {
  font-size: 0.78rem;
  color: var(--ink-soft);
}

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

.boot-note {
  padding-block: 4rem;
}

.boot-note p {
  font-family: var(--serif);
  color: var(--ink-soft);
  max-width: 42em;
}

@media (max-width: 900px) {
  .hero {
    grid-template-columns: 1fr;
    gap: 2.5rem;
    padding-block: 3rem 2.5rem;
  }

  .strip-head {
    grid-template-columns: 1fr;
    gap: 0.8rem;
  }

  .steps {
    grid-template-columns: 1fr;
    gap: 1.8rem;
  }

  .cat-index {
    grid-template-columns: 1fr;
  }

  .lesson-layout {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .lesson-side {
    position: static;
    max-height: none;
    border-bottom: 1px solid var(--line);
    padding-bottom: 1.5rem;
  }

  .course-row {
    grid-template-columns: 1fr;
    gap: 0.35rem;
  }

  .lang-row-link {
    grid-template-columns: 1fr;
    gap: 0.25rem;
  }

  .lang-meta {
    white-space: normal;
  }

  .foot-inner {
    grid-template-columns: 1fr;
    gap: 2rem;
  }

  .lessons {
    padding-left: 0;
  }
}

@media (max-width: 560px) {
  .brand-name {
    display: none;
  }

  .module-head {
    gap: 0.9rem;
  }

  .module-no {
    font-size: 1.3rem;
    min-width: 2.1rem;
  }

  .lesson-nav {
    grid-template-columns: 1fr;
    justify-items: stretch;
  }

  .lesson-step.is-empty {
    display: none;
  }

  .lesson-step.is-forward {
    justify-self: start;
    text-align: left;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    animation: none !important;
    transition: none !important;
    scroll-behavior: auto !important;
  }
}