/* Caffeinated Coder Lab: one stylesheet for the catalog and every lesson.
   Layout: a lab notebook. Mono labels and rules frame an instrument figure; the narrative sits beside its step rail. */
:root {
  --bg: #f2f2ef;
  --surface: #fbfbfa;
  --sunk: #e9e9e5;
  --ink: #18181a;
  --text: #4c4c50;
  --muted: #86868b;
  --rule: #d4d4d6;
  --rule-strong: #18181a;
  --crema: #a8641f;
  --crema-soft: #f1e3d3;
  --good: #2f7a4f;
  --good-soft: #e0efe6;
  --bad: #b23a2e;
  --bad-soft: #f6e1de;
  --sans: "IBM Plex Sans", ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "IBM Plex Mono", ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  --wrap: 1040px;
  color-scheme: light;
}
@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --bg: #0b0b0b; --surface: #131313; --sunk: #1a1a1a; --ink: #ececec; --text: #a6a6a6; --muted: #6f6f72;
    --rule: #262626; --rule-strong: #e6e6e6; --crema: #e3a35e; --crema-soft: #2a1f14;
    --good: #6fc394; --good-soft: #13241a; --bad: #ef8b7f; --bad-soft: #2a1513; color-scheme: dark;
  }
}
:root[data-theme="dark"] {
  --bg: #0b0b0b; --surface: #131313; --sunk: #1a1a1a; --ink: #ececec; --text: #a6a6a6; --muted: #6f6f72;
  --rule: #262626; --rule-strong: #e6e6e6; --crema: #e3a35e; --crema-soft: #2a1f14;
  --good: #6fc394; --good-soft: #13241a; --bad: #ef8b7f; --bad-soft: #2a1513; color-scheme: dark;
}

* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
body { margin: 0; background: var(--bg); color: var(--text); font: 400 16px/1.65 var(--sans); -webkit-font-smoothing: antialiased; }
a { color: var(--ink); text-underline-offset: 3px; text-decoration-thickness: 1px; }
a:hover { color: var(--crema); }
:focus-visible { outline: 2px solid var(--crema); outline-offset: 3px; border-radius: 2px; }
.wrap { max-width: var(--wrap); margin: 0 auto; padding-inline-start: max(16px, env(safe-area-inset-left, 0px)); padding-inline-end: max(16px, env(safe-area-inset-right, 0px)); }
.label { font: 500 11px/1.3 var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); }
h1, h2, h3 { color: var(--ink); font-weight: 500; text-wrap: balance; margin: 0; }
button { font: inherit; color: inherit; }

/* top bar */
.bar { border-bottom: 1px solid var(--rule); }
.bar .wrap { display: flex; align-items: center; gap: 16px; min-height: 56px; flex-wrap: wrap; }
.brand { font: 600 14px/1 var(--mono); letter-spacing: .02em; color: var(--ink); text-decoration: none; display: flex; align-items: center; gap: 10px; }
.brand-mark { width: 18px; height: 18px; border: 1.5px solid var(--ink); border-radius: 0 0 6px 6px; position: relative; }
.brand-mark::after { content: ""; position: absolute; right: -6px; top: 3px; width: 5px; height: 7px; border: 1.5px solid var(--ink); border-left: 0; border-radius: 0 4px 4px 0; }
.brand small { font-weight: 400; color: var(--muted); }
.bar nav { display: flex; gap: 18px; margin-inline-start: auto; align-items: center; font: 400 13px/1 var(--mono); }
.bar nav a { color: var(--text); text-decoration: none; }
.bar nav a:hover, .bar nav a[aria-current="page"] { color: var(--ink); }
.theme { display: inline-flex; border: 1px solid var(--rule); border-radius: 999px; padding: 2px; }
.theme button { border: 0; background: none; padding: 4px 9px; border-radius: 999px; font: 400 11px/1 var(--mono); color: var(--muted); cursor: pointer; }
.theme button[aria-pressed="true"] { background: var(--sunk); color: var(--ink); }

/* lesson header */
.lesson-head { padding-block: 44px 28px; display: grid; grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr); gap: 40px; align-items: end; }
.lesson-head h1 { font-size: clamp(32px, 5.2vw, 52px); line-height: 1.04; letter-spacing: -.025em; margin: 10px 0 14px; }
.lesson-head .lead { margin: 0; max-width: 62ch; }
.meta { display: flex; gap: 8px 18px; flex-wrap: wrap; margin-top: 18px; }
.meta span { font: 400 12px/1 var(--mono); color: var(--muted); }
.meta span b { color: var(--ink); font-weight: 500; }
.learn { border-inline-start: 1px solid var(--rule); padding-inline-start: 24px; }
.learn ul { margin: 10px 0 0; padding: 0; list-style: none; display: grid; gap: 8px; }
.learn li { display: grid; grid-template-columns: 18px 1fr; font-size: 14px; line-height: 1.45; color: var(--ink); }
.learn li::before { content: "→"; font-family: var(--mono); color: var(--crema); }

/* the bench: figure + controls + narrative */
.bench { border-top: 1px solid var(--rule-strong); padding-top: 18px; }
.bench-top { display: flex; justify-content: space-between; align-items: baseline; gap: 12px; flex-wrap: wrap; margin-bottom: 12px; }
.progress { display: flex; align-items: center; gap: 10px; font: 400 12px/1 var(--mono); color: var(--muted); }
.meter { width: 120px; height: 4px; background: var(--sunk); border-radius: 2px; overflow: hidden; }
.meter i { display: block; height: 100%; width: 0; background: var(--crema); transition: width .4s ease; }
.figure-frame { position: relative; min-height: 120px; }
.figure-frame iframe { display: block; width: 100%; height: 420px; border: 0; background: transparent; }
.figure-frame .fallback { position: absolute; inset: 0; display: grid; place-items: center; font: 400 13px/1.4 var(--mono); color: var(--muted); }
.figure-frame.ready .fallback { display: none; }
.controls { display: flex; align-items: center; gap: 8px; padding: 12px 0 0; flex-wrap: wrap; }
.btn { display: inline-flex; align-items: center; gap: 8px; border: 1px solid var(--rule); background: var(--surface); color: var(--ink); padding: 8px 14px; border-radius: 4px; font: 500 13px/1 var(--mono); cursor: pointer; text-decoration: none; }
.btn:hover { border-color: var(--ink); color: var(--ink); }
.btn:disabled { opacity: .4; cursor: default; border-color: var(--rule); }
.btn.primary { background: var(--ink); color: var(--bg); border-color: var(--ink); }
.btn.primary:hover { color: var(--bg); opacity: .88; }
.controls .count { margin-inline-start: auto; font: 400 12px/1 var(--mono); color: var(--muted); }
.kbd { font: 400 11px/1 var(--mono); border: 1px solid var(--rule); border-bottom-width: 2px; border-radius: 3px; padding: 2px 5px; color: var(--muted); }

.narrative { display: grid; grid-template-columns: minmax(220px, 300px) minmax(0, 1fr); gap: 36px; margin-top: 28px; }
.rail { margin: 0; padding: 0; list-style: none; counter-reset: step; }
.rail .chapter { font: 500 11px/1.3 var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); padding: 14px 0 6px; }
.rail .chapter:first-child { padding-top: 0; }
.rail button { all: unset; box-sizing: border-box; display: grid; grid-template-columns: 30px 1fr 14px; gap: 6px; width: 100%; padding: 7px 8px; border-radius: 4px; cursor: pointer; font-size: 14px; line-height: 1.35; color: var(--text); }
.rail button:hover { background: var(--sunk); color: var(--ink); }
.rail button:focus-visible { outline: 2px solid var(--crema); outline-offset: 0; }
.rail .n { font: 400 12px/1.6 var(--mono); color: var(--muted); }
.rail .tick { font: 400 12px/1.6 var(--mono); color: var(--crema); visibility: hidden; }
.rail button.seen .tick { visibility: visible; }
.rail button[aria-current="step"] { background: var(--crema-soft); color: var(--ink); }
.rail button[aria-current="step"] .n { color: var(--crema); }

.panel { min-width: 0; }
.panel .label b { color: var(--crema); font-weight: 500; }
.panel h2 { font-size: clamp(24px, 3vw, 32px); line-height: 1.15; letter-spacing: -.015em; margin: 8px 0 12px; }
.panel p { margin: 0 0 18px; max-width: 64ch; color: var(--text); font-size: 17px; }
.panel pre { margin: 0 0 20px; padding: 14px 16px; background: var(--sunk); border-radius: 4px; font: 400 13px/1.65 var(--mono); color: var(--ink); overflow-x: auto; white-space: pre; }
.panel-nav { display: flex; gap: 8px; flex-wrap: wrap; }

/* sections below the bench */
.section { border-top: 1px solid var(--rule); margin-top: 56px; padding-top: 22px; display: grid; grid-template-columns: minmax(180px, 260px) minmax(0, 1fr); gap: 36px; }
.section > header h2 { font-size: 22px; letter-spacing: -.01em; margin-top: 8px; }
.section > header p { font-size: 14px; color: var(--muted); margin: 8px 0 0; }

.quiz { display: grid; gap: 28px; }
.q h3 { font-size: 18px; line-height: 1.35; margin-bottom: 12px; display: grid; grid-template-columns: 30px 1fr; }
.q h3 span { font: 400 13px/1.9 var(--mono); color: var(--muted); }
.opts { display: grid; gap: 6px; margin-inline-start: 30px; }
.opt { all: unset; box-sizing: border-box; display: grid; grid-template-columns: 26px 1fr; padding: 10px 12px; border: 1px solid var(--rule); border-radius: 4px; cursor: pointer; font-size: 15px; line-height: 1.4; color: var(--ink); background: var(--surface); }
.opt:hover { border-color: var(--ink); }
.opt:focus-visible { outline: 2px solid var(--crema); outline-offset: 1px; }
.opt span { font: 400 12px/1.7 var(--mono); color: var(--muted); }
.opt[data-state="right"] { border-color: var(--good); background: var(--good-soft); }
.opt[data-state="wrong"] { border-color: var(--bad); background: var(--bad-soft); }
.opt[data-state="dim"] { opacity: .55; }
.q.done .opt { cursor: default; }
.q.done .opt:hover { border-color: var(--rule); }
.q.done .opt[data-state="right"]:hover { border-color: var(--good); }
.q.done .opt[data-state="wrong"]:hover { border-color: var(--bad); }
.explain { margin: 10px 0 0; margin-inline-start: 30px; font-size: 14px; color: var(--text); display: none; }
.explain b { font: 500 11px/1 var(--mono); letter-spacing: .1em; text-transform: uppercase; margin-inline-end: 8px; }
.q.done .explain { display: block; }
.q.done.correct .explain b { color: var(--good); }
.q.done.missed .explain b { color: var(--bad); }
.score { display: flex; align-items: center; gap: 14px; flex-wrap: wrap; padding: 16px 0 0; border-top: 1px solid var(--rule); font: 400 13px/1.4 var(--mono); color: var(--muted); }
.score b { font: 500 22px/1 var(--sans); color: var(--ink); }

.terms { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 0 32px; margin: 0; }
.terms div { padding: 12px 0; border-bottom: 1px solid var(--rule); }
.terms dt { color: var(--ink); font-weight: 500; font-size: 15px; }
.terms dd { margin: 4px 0 0; font-size: 14px; line-height: 1.5; }
.notes { margin: 0; padding: 0; list-style: none; display: grid; gap: 10px; font-size: 14px; }
.sources { margin: 18px 0 0; padding: 0; list-style: none; display: grid; gap: 6px; font-size: 14px; }
.sources a::after { content: " ↗"; color: var(--muted); }

.next { margin: 56px 0 0; border-top: 1px solid var(--rule-strong); padding: 22px 0 64px; display: flex; justify-content: space-between; gap: 20px; flex-wrap: wrap; align-items: center; }
.next a.card { text-decoration: none; display: grid; gap: 4px; }
.next a.card strong { font-size: 22px; color: var(--ink); font-weight: 500; letter-spacing: -.01em; }
.next a.card:hover strong { color: var(--crema); }

/* catalog */
.hero { padding-block: 56px 36px; display: grid; grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr); gap: 40px; align-items: end; }
.hero h1 { font-size: clamp(36px, 6vw, 64px); line-height: 1; letter-spacing: -.03em; margin-top: 12px; }
.hero p { margin: 0; max-width: 46ch; }
.tracks { border-top: 1px solid var(--rule-strong); padding-top: 14px; margin-bottom: 64px; }
.lessons { list-style: none; margin: 14px 0 0; padding: 0; display: grid; grid-template-columns: repeat(auto-fill, minmax(min(100%, 320px), 1fr)); gap: 16px; }
.lesson-card { display: grid; grid-template-rows: auto auto 1fr auto; gap: 10px; padding: 16px; height: 100%; border: 1px solid var(--rule); border-radius: 4px; background: var(--surface); text-decoration: none; color: var(--text); }
.lesson-card:hover { border-color: var(--ink); color: var(--text); }
.lesson-card .thumb { aspect-ratio: 900 / 370; max-width: 100%; border-radius: 2px; overflow: hidden; background: var(--sunk); }
.lesson-card .thumb img { width: 100%; height: 100%; object-fit: cover; display: block; }
.lesson-card .thumb .dark { display: none; }
@media (prefers-color-scheme: dark) { :root:not([data-theme="light"]) .lesson-card .thumb .light { display: none; } :root:not([data-theme="light"]) .lesson-card .thumb .dark { display: block; } }
:root[data-theme="dark"] .lesson-card .thumb .light { display: none; }
:root[data-theme="dark"] .lesson-card .thumb .dark { display: block; }
.lesson-card h2 { font-size: 21px; line-height: 1.2; letter-spacing: -.01em; }
.lesson-card p { margin: 0; font-size: 14px; line-height: 1.5; }
.lesson-card .foot { display: flex; justify-content: space-between; align-items: center; gap: 10px; font: 400 12px/1 var(--mono); color: var(--muted); padding-top: 10px; border-top: 1px solid var(--rule); }
.status { font: 500 11px/1 var(--mono); letter-spacing: .08em; text-transform: uppercase; padding: 4px 7px; border-radius: 3px; background: var(--sunk); color: var(--muted); }
.status[data-s="started"] { background: var(--crema-soft); color: var(--crema); }
.status[data-s="done"] { background: var(--good-soft); color: var(--good); }

.site-foot { border-top: 1px solid var(--rule); padding-block: 20px 40px; font: 400 12px/1.5 var(--mono); color: var(--muted); }

@media (max-width: 820px) {
  .lesson-head, .hero { grid-template-columns: 1fr; gap: 24px; }
  .learn { border-inline-start: 0; border-top: 1px solid var(--rule); padding: 18px 0 0; }
  .narrative, .section { grid-template-columns: 1fr; gap: 20px; }
  .rail { display: flex; gap: 6px; overflow-x: auto; padding-bottom: 6px; scrollbar-width: thin; }
  .rail .chapter { display: none; }
  .rail li { flex: 0 0 auto; }
  .rail button { grid-template-columns: auto; padding: 6px 10px; border: 1px solid var(--rule); }
  .rail button .t, .rail button .tick { display: none; }
  .rail button.seen { border-color: var(--crema); }
  .terms { grid-template-columns: 1fr; }
  .figure-frame iframe { height: 260px; }
  .controls .hint { display: none; }
}
@media (prefers-reduced-motion: reduce) { .meter i { transition: none; } }

/* v2: wider bench, graphical timeline, explanation lives in the figure */
:root { --wrap: 1200px; }
.timeline { display: flex; gap: 10px; margin-top: 16px; }
.seg { min-width: 0; }
.seg-title { font: 500 10.5px/1.2 var(--mono); letter-spacing: .1em; text-transform: uppercase; color: var(--muted); padding-bottom: 6px; border-bottom: 1px solid var(--rule); margin-bottom: 8px; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.dots { display: flex; justify-content: space-between; gap: 2px; }
.dots button { all: unset; box-sizing: border-box; flex: 1; display: grid; place-items: center; height: 22px; cursor: pointer; border-radius: 3px; }
.dots button i { width: 10px; height: 10px; border-radius: 50%; border: 1.5px solid var(--muted); background: transparent; transition: transform .2s, background .2s, border-color .2s; }
.dots button:hover i { border-color: var(--ink); transform: scale(1.2); }
.dots button.seen i { background: var(--muted); border-color: var(--muted); }
.dots button[aria-current="step"] i { background: var(--crema); border-color: var(--crema); transform: scale(1.35); box-shadow: 0 0 0 4px var(--crema-soft); }
.dots button:focus-visible { outline: 2px solid var(--crema); }
.narrow-only { display: none; }
.panel h2 { font-size: clamp(20px, 2.4vw, 26px); }
@media (max-width: 820px) {
  .narrow-only { display: none; }
  .timeline { overflow-x: auto; }
  .seg { flex: none !important; }
  .dots button { flex: none; width: 22px; }
  .rail { display: none; }
}

/* v3: no text under the figure; the quiz unlocks after the last step */
.done-banner { margin-top: 48px; padding: 22px 24px; border-radius: 6px; background: var(--crema-soft); border-inline-start: 3px solid var(--crema); }
.done-banner h2 { font-size: 24px; margin: 6px 0 4px; }
.done-banner p { margin: 0; color: var(--text); }
.locked { margin: 40px 0 0; padding: 14px 0; border-top: 1px dashed var(--rule); font-size: 14px; color: var(--muted); display: flex; gap: 12px; align-items: center; }
.locked::before { content: ""; width: 14px; height: 14px; border: 1.5px solid var(--muted); border-radius: 3px; box-shadow: inset 0 -5px 0 -3px var(--muted); }
.quiz-cta { margin-inline-start: 8px; }
.after[hidden], .quiz-cta[hidden], .locked[hidden] { display: none !important; }
.bench { padding-bottom: 8px; }

/* Course and account pages share the notebook's type, rules and crema accent. */
[hidden] { display: none !important; }
.bar .account-chip { display: inline-block; max-width: 180px; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; border: 1px solid var(--rule); border-radius: 4px; padding: 7px 10px; }
.breadcrumb { display: flex; align-items: baseline; flex-wrap: wrap; gap: 6px 10px; padding-top: 24px; font: 400 12px/1.6 var(--mono); }
.breadcrumb a { color: var(--text); text-decoration: none; }
.breadcrumb > span { color: var(--muted); }
.breadcrumb + .lesson-head { padding-top: 24px; }
.course-catalog { padding-bottom: 16px; }
.course-catalog .course-feature > div { min-width: 0; }
.continue-course { margin-top: 10px; color: var(--crema); }
.course-feature { border-top: 1px solid var(--rule-strong); padding: 28px 0 64px; display: grid; grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr); gap: 56px; }
.course-feature h2 { font-size: clamp(27px, 3vw, 36px); line-height: 1.2; letter-spacing: -.02em; margin-top: 12px; }
.course-feature h2 a { text-decoration: none; }
.course-feature p { margin: 14px 0 0; max-width: 65ch; }
.course-feature-progress { align-self: end; border-inline-start: 1px solid var(--rule); padding-inline-start: 32px; }
.course-progress { display: grid; gap: 10px; font: 400 12px/1.5 var(--mono); color: var(--text); }
.course-progress .meter { width: 100%; height: 5px; }
.course-feature-progress .course-progress { margin: 14px 0 22px; }
.continue-card { display: flex; justify-content: space-between; align-items: center; gap: 24px; border-top: 1px solid var(--rule); padding: 24px 0; margin-bottom: 20px; }
.continue-card h2 { font-size: 24px; line-height: 1.25; margin-top: 8px; }
.continue-card p { font: 400 12px/1.5 var(--mono); margin: 8px 0 0; }
.continue-card .btn { flex-shrink: 0; }
.course-head { padding: 48px 0 38px; max-width: 820px; }
.course-head h1, .account-head h1 { font-size: clamp(36px, 5vw, 56px); line-height: 1.06; letter-spacing: -.025em; margin: 12px 0 18px; }
.course-head .lead { max-width: 68ch; margin: 0; }
.course-head .course-progress { margin-top: 28px; max-width: 540px; }
.module-section { border-top: 1px solid var(--rule-strong); padding-top: 22px; margin-bottom: 48px; scroll-margin-top: 24px; }
.module-head { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1.5fr); gap: 32px; align-items: end; }
.module-head h2 { font-size: 28px; line-height: 1.2; letter-spacing: -.015em; margin-top: 10px; }
.module-head p { margin: 0; max-width: 68ch; font-size: 15px; }
.level-chip { display: inline-block; margin-inline-start: 12px; padding: 4px 6px; border: 1px solid var(--rule); border-radius: 3px; color: var(--text); font-size: 10px; letter-spacing: .04em; }
.course-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); margin-top: 22px; gap: 12px; }
.course-lesson { grid-template-rows: auto 1fr auto; gap: 14px; min-height: 156px; }
.course-lesson h3 { font-size: 20px; line-height: 1.25; letter-spacing: -.01em; }
.course-lesson .foot { flex-wrap: wrap; line-height: 1.3; }
.course-lesson.coming-soon { background: transparent; border-style: dashed; }
.course-lesson.coming-soon:hover { border-color: var(--rule); }
.coming-soon h3 { color: var(--text); }
.coming-soon .label { color: var(--muted); }
.coming-soon .foot { border-top: 0; padding-top: 0; }
.special-section .course-lesson { grid-template-rows: auto 1fr auto auto; }
.course-lesson .builds-on { font: 400 12px/1.5 var(--mono); color: var(--text); }
.account-wrap { max-width: 1000px; padding-bottom: 64px; min-height: calc(100vh - 160px); }
.account-head { padding-top: 48px; max-width: 650px; }
.account-head p { margin-bottom: 0; }
.account-message { min-height: 1.5em; margin: 20px 0; font-size: 14px; }
.account-message:empty { display: none; }
.server-required { border: 1px solid var(--rule); padding: 18px 20px; background: var(--surface); }
.server-required code { font: 400 13px/1.5 var(--mono); color: var(--ink); }
.account-forms { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 48px; margin-top: 32px; }
.account-section { border-top: 1px solid var(--rule); padding-top: 20px; }
.account-section h2 { margin: 8px 0 22px; font-size: 26px; line-height: 1.2; letter-spacing: -.015em; }
.account-section > p { margin-top: -8px; font-size: 14px; }
.account-section form { display: grid; gap: 16px; }
.account-section label { display: grid; gap: 6px; font-size: 14px; color: var(--ink); }
.account-section input:not([type="checkbox"]) { display: block; width: 100%; min-width: 0; border: 1px solid var(--rule); border-radius: 4px; background: var(--surface); color: var(--ink); padding: 10px 12px; font: 400 16px/1.4 var(--sans); }
.account-section input:not([type="checkbox"]):focus { border-color: var(--crema); }
.account-section .btn { justify-self: start; min-height: 38px; }
.form-help { font-size: 13px; margin: -10px 0 0; color: var(--text); }
.form-message { font-size: 14px; margin: 0; overflow-wrap: anywhere; }
.form-message:empty { display: none; }
.form-message[data-state="error"], .account-message[data-state="error"] { color: var(--bad); }
.form-message[data-state="success"], .account-message[data-state="success"] { color: var(--good); }
.account-identity { display: flex; justify-content: space-between; align-items: center; gap: 24px; border-top: 1px solid var(--rule-strong); padding: 22px 0; margin-top: 24px; }
.account-identity p { margin: 6px 0 0; color: var(--ink); overflow-wrap: anywhere; }
.account-identity > div { min-width: 0; }
.account-identity .btn { flex-shrink: 0; }
.account-section .checkbox-label { grid-template-columns: 18px minmax(0, 1fr); gap: 10px; align-items: start; line-height: 1.5; }
.checkbox-label input { width: 16px; height: 16px; margin: 3px 0 0; accent-color: var(--crema); }
.btn.danger { color: var(--bad); border-color: var(--bad); }
@media (max-width: 820px) {
  .course-feature, .module-head { grid-template-columns: 1fr; gap: 20px; }
  .course-feature-progress { border-inline-start: 0; padding-inline-start: 0; max-width: 520px; }
  .course-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .account-forms { gap: 28px; }
}
@media (max-width: 560px) {
  .bar .wrap { gap: 14px; padding-top: 16px; padding-bottom: 14px; }
  .bar nav { margin-inline-start: 0; width: 100%; justify-content: space-between; gap: 10px; }
  .bar .account-chip { max-width: 95px; }
  .course-grid, .account-forms { grid-template-columns: 1fr; }
  .course-head, .account-head { padding-top: 32px; }
  .course-head { padding-bottom: 28px; }
  .course-feature { padding-bottom: 40px; }
  .module-head { gap: 14px; }
  .module-section { margin-bottom: 36px; }
  .continue-card { align-items: start; flex-direction: column; gap: 16px; }
  .account-forms { gap: 36px; }
  .account-identity { gap: 12px; }
}

/* Arabic chrome uses locally installed, Arabic-capable system fonts. Technical
   surfaces and drawings preserve their own LTR coordinate systems. */
html[lang="ar"] { --sans: "Noto Sans Arabic", "IBM Plex Sans Arabic", Tahoma, "Segoe UI", Arial, sans-serif; --mono: "IBM Plex Mono", "SF Mono", Menlo, Consolas, "Noto Sans Arabic", Tahoma, monospace; }
html[lang="ar"] .label, html[lang="ar"] .bar nav, html[lang="ar"] .btn, html[lang="ar"] .meta span, html[lang="ar"] .theme button { letter-spacing: 0; line-height: 1.55; }
html[lang="ar"] h1, html[lang="ar"] h2, html[lang="ar"] h3 { line-height: 1.5; letter-spacing: 0; }
html[dir="rtl"] .learn li::before { content: "←"; }
html[dir="rtl"] .breadcrumb > span[aria-hidden="true"] { transform: scaleX(-1); }
html[dir="rtl"] .bar nav { flex-wrap: wrap; }
html[dir="rtl"] .header-search label { width: auto; }
.language-switch { white-space: nowrap; }
.translation-fallback { display: inline-block; margin: 0 0 12px; padding: 4px 10px; border: 1px solid var(--rule); border-radius: 4px; color: var(--text); font-size: 12px; }
.figure-frame, .logic-stage, .logic-scroll, .net-stage, .net-canvas, .cpu-registers, .cpu-memory, .cpu-listing, .cpu-lab textarea, .exercise-editor, .exercise-shown-code, [data-exercise-output], pre, code { direction: ltr; }
html[dir="rtl"] pre, html[dir="rtl"] textarea, html[dir="rtl"] [data-exercise-output] { text-align: left; unicode-bidi: plaintext; }
html[dir="rtl"] .exercise-editor { text-align: left; }
html[dir="rtl"] .exercise-editor pre { text-align: right; }
@media (max-width: 700px) {
  .bar nav { flex-wrap: wrap; }
  html[dir="rtl"] .bar nav { row-gap: 14px; padding-block: 8px; }
  html[dir="rtl"] .theme { margin-inline-start: 0; }
  html[dir="rtl"] .certificate-paper { padding-inline: 18px; }
}