:root {
  --ink: #15252f;
  --ink-soft: #334b58;
  --muted: #6f7f87;
  --line: #d8e0e3;
  --line-strong: #c4d0d5;
  --paper: #ffffff;
  --wash: #f2f5f5;
  --wash-2: #e9eff0;
  --sidebar: #172630;
  --sidebar-soft: #233640;
  --accent: #4d7485;
  --accent-pale: #e7eef1;
  --serif: Georgia, "Times New Roman", serif;
  --sans: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}
* { box-sizing: border-box; }
html { color-scheme: light; background: var(--wash); scroll-behavior: smooth; }
body { margin: 0; min-width: 320px; color: var(--ink); background: linear-gradient(90deg, #eef1f1 0, #eef1f1 17%, #f6f7f7 17%, #f6f7f7 100%); font-family: var(--sans); line-height: 1.62; }
button, input { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }
a { color: inherit; }
button:focus-visible, a:focus-visible, input:focus-visible, summary:focus-visible { outline: 3px solid rgba(77,116,133,.3); outline-offset: 3px; }
.skip-link { position: fixed; z-index: 100; top: 10px; left: 10px; transform: translateY(-160%); padding: 10px 14px; border-radius: 8px; background: #fff; color: var(--ink); }
.skip-link:focus { transform: none; }
.mobile-header { display: none; }
.sidebar { position: fixed; z-index: 20; inset: 0 auto 0 0; width: 334px; color: #edf3f4; background: var(--sidebar); }
.sidebar-inner { display: flex; min-height: 100%; flex-direction: column; padding: 36px 30px 28px; }
.sidebar-head { display: flex; align-items: center; justify-content: space-between; }
.brand { display: inline-flex; align-items: center; gap: 12px; color: #fff; font-size: 12px; letter-spacing: .16em; text-decoration: none; }
.brand b { color: #b8ced7; font-weight: 700; }
.brand-mark { display: grid; width: 32px; height: 32px; place-items: center; border: 1px solid rgba(225,238,242,.55); border-radius: 50%; font-family: var(--serif); font-size: 15px; letter-spacing: 0; }
.menu-close { display: none; border: 0; background: transparent; color: white; font-size: 28px; }
.course-identity { margin-top: 68px; }
.pill { display: inline-block; padding: 6px 11px; border: 1px solid rgba(202,221,227,.2); border-radius: 999px; background: rgba(255,255,255,.04); color: #c8dbe2; font-size: 11px; font-weight: 700; letter-spacing: .05em; text-transform: uppercase; }
.course-identity h2 { margin: 21px 0 34px; font-family: var(--serif); font-size: 27px; font-weight: 500; letter-spacing: -.03em; }
.progress-copy { display: flex; justify-content: space-between; color: #aac4cf; font-size: 12px; }
.progress-track { height: 4px; margin-top: 9px; overflow: hidden; border-radius: 999px; background: rgba(207,226,232,.16); }
.progress-track span { display: block; width: 0; height: 100%; background: #b3cad3; transition: width .25s ease; }
.lesson-nav { display: grid; gap: 8px; margin-top: 34px; }
.lesson-nav button { display: grid; grid-template-columns: 30px 1fr 16px; gap: 12px; align-items: center; min-height: 62px; padding: 9px 12px; border: 0; border-radius: 11px; color: #d5e1e5; background: transparent; text-align: left; cursor: pointer; }
.lesson-nav button:hover { background: rgba(255,255,255,.05); }
.lesson-nav button.active { background: rgba(216,231,236,.1); color: #fff; }
.lesson-nav button > span:nth-child(2) { display: grid; }
.lesson-nav b { font-size: 13px; font-weight: 650; }
.lesson-nav small { color: #8faab5; font-size: 11px; }
.lesson-nav i { color: #8faab5; font-size: 22px; font-style: normal; }
.step-dot { display: grid; width: 28px; height: 28px; place-items: center; border: 1px solid rgba(206,224,230,.28); border-radius: 50%; color: #bcd0d7; font-size: 11px; }
.lesson-nav button.complete .step-dot { border-color: #bfd1d8; background: #bfd1d8; color: var(--sidebar); }
.sidebar-note { display: flex; gap: 10px; align-items: flex-start; margin-top: auto; padding-top: 26px; border-top: 1px solid rgba(211,227,232,.12); color: #89a6b1; font-size: 11px; }
.sidebar-note p { margin: 0; }
.course-main { min-height: 100vh; margin-left: 334px; padding: 0 5vw; }
.lesson-sheet { width: min(920px, 100%); min-height: 100vh; margin: 0 auto; padding: 66px clamp(54px, 6vw, 94px) 44px; background: var(--paper); box-shadow: 0 0 0 1px rgba(34,60,72,.06); }
.screen { display: none; animation: enter .28s ease both; }
.screen.is-active { display: block; }
@keyframes enter { from { opacity: 0; transform: translateY(5px); } to { opacity: 1; transform: none; } }
.intro-screen { padding-top: 34px; }
.intro-kicker, .eyebrow { display: flex; gap: 9px; align-items: center; margin: 0 0 24px; color: var(--accent); font-size: 11px; font-weight: 750; letter-spacing: .11em; }
.intro-kicker span { width: 30px; height: 1px; background: var(--accent); }
.intro-screen h1, .lesson-content > h1, .completion-screen h1 { margin: 0; font-family: var(--serif); font-size: clamp(50px, 6vw, 76px); font-weight: 400; letter-spacing: -.055em; line-height: .97; }
.intro-screen h1 em, .completion-screen h1 em { color: var(--accent); font-weight: 400; }
.lead { max-width: 670px; margin: 28px 0 36px; color: var(--ink-soft); font-family: var(--serif); font-size: 21px; line-height: 1.55; }
.intro-facts { display: grid; grid-template-columns: repeat(3, 1fr); margin: 40px 0 34px; border-block: 1px solid var(--line); }
.intro-facts > div { display: flex; gap: 13px; align-items: center; min-height: 98px; padding: 18px 14px; border-right: 1px solid var(--line); }
.intro-facts > div:first-child { padding-left: 0; }
.intro-facts > div:last-child { border-right: 0; }
.fact-symbol { display: grid; width: 36px; height: 36px; flex: 0 0 auto; place-items: center; border-radius: 10px; background: var(--accent-pale); color: var(--accent); font-family: var(--serif); font-size: 15px; }
.intro-facts p { display: grid; margin: 0; }
.intro-facts b { font-size: 13px; }
.intro-facts small { color: var(--muted); font-size: 11px; }
.intro-actions, .completion-actions { display: flex; flex-wrap: wrap; gap: 12px; align-items: center; }
.intro-actions > small { width: 100%; color: var(--muted); font-size: 11px; }
.primary-button, .next-button { display: inline-flex; min-height: 50px; align-items: center; justify-content: center; gap: 18px; padding: 0 22px; border: 1px solid var(--sidebar); border-radius: 8px; background: var(--sidebar); color: #fff; font-size: 13px; font-weight: 700; text-decoration: none; cursor: pointer; }
.primary-button:hover, .next-button:hover { background: #223a46; }
.share-button, .previous-button, .text-button, .prompt-box button, .example-panel button, .built-prompt button { min-height: 46px; padding: 0 17px; border: 1px solid var(--line-strong); border-radius: 8px; background: #fff; color: var(--ink); font-size: 12px; font-weight: 650; cursor: pointer; }
.share-button:hover, .previous-button:hover, .prompt-box button:hover, .example-panel button:hover, .built-prompt button:hover { border-color: var(--accent); }
.text-button { border-color: transparent; color: var(--muted); }
.learning-strip { margin-top: 50px; padding: 22px 0; border-top: 1px solid var(--line); }
.learning-strip > p { margin: 0 0 13px; color: var(--muted); font-size: 11px; font-weight: 700; letter-spacing: .09em; text-transform: uppercase; }
.learning-strip ul { display: flex; flex-wrap: wrap; gap: 9px 22px; margin: 0; padding: 0; list-style: none; color: var(--ink-soft); font-size: 13px; }
.learning-strip li::first-letter { color: var(--accent); }
.lesson-content > h1 { font-size: clamp(43px, 5vw, 62px); }
.lesson-content > p:not(.lead):not(.source-note) { margin: 18px 0; color: #344a55; font-size: 16px; }
.concept-card { display: grid; grid-template-columns: 65px 1fr; gap: 24px; margin: 39px 0; padding: 30px; border-block: 1px solid var(--line); background: var(--wash); }
.concept-card .number { color: var(--accent); font-family: var(--serif); font-size: 34px; }
.concept-card small, .example-panel small, .built-prompt small { color: var(--accent); font-size: 10px; font-weight: 750; letter-spacing: .1em; }
.concept-card h2 { margin: 8px 0 12px; font-family: var(--serif); font-size: 28px; font-weight: 500; line-height: 1.2; }
.concept-card p { margin: 0; color: var(--muted); font-size: 14px; }
.callout { display: grid; grid-template-columns: 46px 1fr; gap: 18px; margin: 34px 0; padding: 26px 28px; border: 1px solid var(--line); border-radius: 11px; background: #f8fafa; }
.callout.quiet { background: var(--wash); }
.callout-mark { display: grid; width: 44px; height: 44px; place-items: center; border-radius: 10px; background: var(--accent-pale); color: var(--accent); font-size: 10px; font-weight: 750; }
.callout h3 { margin: 1px 0 7px; font-family: var(--serif); font-size: 20px; font-weight: 500; }
.callout p { margin: 0 0 14px; color: var(--ink-soft); font-size: 14px; }
.prompt-box, .example-panel, .built-prompt { display: flex; gap: 18px; align-items: center; justify-content: space-between; margin-top: 15px; padding: 17px 18px; border: 1px solid var(--line); border-radius: 8px; background: #fff; }
.prompt-box p, .built-prompt p { margin: 0; color: var(--ink); font-family: var(--serif); font-size: 16px; }
.prompt-box button, .example-panel button, .built-prompt button { min-height: 38px; flex: 0 0 auto; }
.source-note { margin: 30px 0 0; color: var(--muted); font-size: 12px; }
.source-note a { color: var(--accent); }
.choice-heading { display: flex; align-items: end; justify-content: space-between; gap: 20px; margin-top: 40px; padding-bottom: 12px; border-bottom: 1px solid var(--line); }
.choice-heading h2 { margin: 0; font-family: var(--serif); font-size: 22px; font-weight: 500; }
.choice-heading p { margin: 0; color: var(--muted); font-size: 12px; }
.use-list { display: grid; }
.use-choice { display: grid; grid-template-columns: 34px 1fr auto; gap: 18px; align-items: center; min-height: 88px; padding: 18px 8px; border: 0; border-bottom: 1px solid var(--line); background: transparent; color: var(--ink); text-align: left; cursor: pointer; }
.use-choice:hover, .use-choice.open { padding-inline: 14px; background: var(--wash); }
.use-choice > span { color: var(--accent); font-size: 11px; font-weight: 750; letter-spacing: .08em; }
.use-choice h3 { margin: 0; font-family: var(--serif); font-size: 17px; font-weight: 500; }
.use-choice p { margin: 3px 0 0; color: var(--muted); font-size: 12px; }
.use-choice > b { color: var(--accent); font-size: 11px; font-weight: 650; }
.example-panel { margin: 14px 0 24px; background: var(--wash); }
.example-panel p { margin: 5px 0 0; font-family: var(--serif); font-size: 16px; }
.custom-task { display: grid; grid-template-columns: 1fr 1.3fr; gap: 28px; margin-top: 32px; padding: 25px 27px; border: 1px solid var(--line); border-radius: 11px; background: #f8fafa; }
.custom-task h3 { margin: 0; font-family: var(--serif); font-size: 19px; font-weight: 500; }
.custom-task p { margin: 6px 0 0; color: var(--muted); font-size: 12px; }
.custom-task label, .prompt-builder label { color: var(--ink-soft); font-size: 11px; font-weight: 700; }
.custom-task input, .prompt-builder input { width: 100%; height: 46px; margin-top: 7px; padding: 0 13px; border: 1px solid var(--line-strong); border-radius: 7px; background: #fff; color: var(--ink); font-size: 14px; font-weight: 400; }
.rule-line { display: flex; gap: 18px; margin-top: 26px; padding-top: 18px; border-top: 1px solid var(--line); }
.rule-line span { color: var(--accent); font-size: 11px; font-weight: 750; text-transform: uppercase; }
.rule-line p { margin: 0; color: var(--ink-soft); font-size: 13px; }
.formula { display: grid; grid-template-columns: 1fr auto 1fr auto 1fr; gap: 12px; align-items: center; margin: 39px 0; }
.formula > div { display: flex; gap: 12px; align-items: flex-start; min-height: 95px; padding: 18px 15px; border: 1px solid var(--line); border-radius: 9px; background: var(--wash); }
.formula > div > span { display: grid; width: 25px; height: 25px; flex: 0 0 auto; place-items: center; border-radius: 50%; background: var(--accent); color: #fff; font-size: 11px; }
.formula p { display: grid; margin: 0; }
.formula b { font-size: 13px; }
.formula small { margin-top: 5px; color: var(--muted); font-size: 11px; line-height: 1.45; }
.formula > i { color: var(--accent); font-style: normal; }
.comparison { display: grid; grid-template-columns: 1fr auto 1fr; gap: 18px; align-items: center; margin: 30px 0; }
.comparison > div { min-height: 112px; padding: 20px; border-left: 3px solid var(--line-strong); background: var(--wash); }
.comparison > div:last-child { border-color: var(--accent); }
.comparison small { color: var(--muted); font-size: 10px; font-weight: 750; letter-spacing: .1em; }
.comparison p { margin: 8px 0 0; font-family: var(--serif); font-size: 15px; line-height: 1.5; }
.builder-wrap { min-width: 0; }
.prompt-builder { display: grid; grid-template-columns: repeat(3, 1fr); gap: 10px; margin-top: 18px; }
.built-prompt { align-items: flex-end; margin-top: 13px; }
.built-prompt > p { flex: 1; }
.built-prompt button:disabled { cursor: default; opacity: .5; }
.risk-scale { display: grid; grid-template-columns: 1fr 38px 1fr; gap: 15px; align-items: center; margin: 38px 0; }
.risk-scale > div { min-height: 154px; padding: 25px; border: 1px solid var(--line); border-radius: 10px; }
.risk-scale > div:first-child { background: #f7f9f9; }
.risk-scale > div:last-child { background: #f3f5f5; }
.risk-scale > span { height: 1px; background: var(--line-strong); }
.risk-scale small { color: var(--accent); font-size: 10px; font-weight: 750; text-transform: uppercase; }
.risk-scale h3 { margin: 10px 0 8px; font-family: var(--serif); font-size: 19px; font-weight: 500; }
.risk-scale p { margin: 0; color: var(--muted); font-size: 12px; }
.big-rule { margin: 0 !important; font-family: var(--serif); font-size: 20px !important; }
.quiz-card { min-width: 0; margin: 36px 0 0; padding: 28px; border: 1px solid var(--line); border-radius: 11px; }
.quiz-card legend { padding: 0 8px; color: var(--accent); font-size: 10px; font-weight: 750; letter-spacing: .1em; }
.quiz-card h2 { margin: 0 0 22px; font-family: var(--serif); font-size: 22px; font-weight: 500; }
.quiz-card > label { display: grid; grid-template-columns: 20px 25px 1fr; gap: 12px; align-items: center; min-height: 52px; margin-top: 8px; padding: 10px 13px; border: 1px solid var(--line); border-radius: 8px; cursor: pointer; }
.quiz-card > label:has(input:checked) { border-color: var(--accent); background: var(--wash); }
.quiz-card input { accent-color: var(--accent); }
.quiz-card label b { color: var(--accent); font-size: 12px; }
.quiz-card label span { font-size: 13px; }
.quiz-feedback { margin-top: 15px; padding: 14px 16px; border-left: 3px solid var(--accent); background: var(--wash); color: var(--ink-soft); font-size: 13px; }
.quiz-feedback strong { color: var(--ink); }
.safety-list { display: grid; margin: 38px 0; border-top: 1px solid var(--line); }
.safety-list > div { display: grid; grid-template-columns: 55px 1fr; gap: 20px; padding: 22px 6px; border-bottom: 1px solid var(--line); }
.safety-list > div > span { color: var(--accent); font-family: var(--serif); font-size: 23px; }
.safety-list h3 { margin: 0; font-family: var(--serif); font-size: 20px; font-weight: 500; }
.safety-list p { margin: 4px 0 0; color: var(--muted); font-size: 13px; }
.comparison.privacy > div:first-child { border-color: #9d8f86; }
.check-list { display: grid; gap: 9px; margin-top: 15px; }
.check-list label { display: flex; gap: 10px; align-items: flex-start; color: var(--ink-soft); font-size: 13px; cursor: pointer; }
.check-list input { margin-top: 4px; accent-color: var(--accent); }
.lesson-footer { display: flex; align-items: center; justify-content: space-between; margin-top: 48px; padding-top: 22px; border-top: 1px solid var(--line); }
.lesson-footer > span { color: var(--muted); font-size: 11px; }
.next-button:disabled { border-color: var(--line-strong); background: var(--line-strong); cursor: not-allowed; }
.completion-screen { padding-top: 20px; text-align: center; }
.completion-mark { display: grid; width: 54px; height: 54px; margin: 0 auto 18px; place-items: center; border-radius: 50%; background: var(--sidebar); color: #fff; font-size: 22px; }
.completion-kicker { color: var(--accent); font-size: 11px; font-weight: 750; letter-spacing: .12em; }
.completion-screen .lead { margin-inline: auto; }
.takeaways { display: grid; grid-template-columns: 1fr 1fr; gap: 1px; margin: 38px 0; border: 1px solid var(--line); background: var(--line); text-align: left; }
.takeaways > div { display: grid; grid-template-columns: 34px 1fr; gap: 12px; padding: 22px; background: #fff; }
.takeaways > div > span { color: var(--accent); font-family: var(--serif); font-size: 18px; }
.takeaways p { display: grid; margin: 0; color: var(--muted); font-size: 12px; }
.takeaways b { margin-bottom: 4px; color: var(--ink); font-family: var(--serif); font-size: 17px; font-weight: 500; }
.completion-actions { justify-content: center; }
.sources-panel { margin-top: 42px; border-top: 1px solid var(--line); text-align: left; }
.sources-panel summary { padding: 17px 0; color: var(--ink-soft); font-size: 12px; font-weight: 650; cursor: pointer; }
.sources-panel div { padding-bottom: 20px; color: var(--muted); font-size: 12px; }
.sources-panel a { color: var(--accent); }
.toast { position: fixed; z-index: 50; left: 50%; bottom: 26px; transform: translate(-50%, 18px); padding: 10px 15px; border-radius: 7px; background: var(--sidebar); color: #fff; font-size: 12px; opacity: 0; pointer-events: none; transition: .2s ease; }
.toast.show { transform: translate(-50%, 0); opacity: 1; }
.scrim { display: none; }

@media (max-width: 1050px) {
  .sidebar { width: 290px; }
  .course-main { margin-left: 290px; padding: 0 3vw; }
  .lesson-sheet { padding-inline: 48px; }
}
@media (max-width: 820px) {
  body { background: var(--wash); }
  .mobile-header { position: sticky; z-index: 16; top: 0; display: flex; height: 64px; align-items: center; justify-content: space-between; padding: 0 18px; background: var(--sidebar); }
  .menu-toggle { border: 1px solid rgba(255,255,255,.23); border-radius: 7px; background: transparent; color: #fff; padding: 7px 11px; font-size: 12px; }
  .sidebar { width: min(335px, 88vw); transform: translateX(-102%); transition: transform .24s ease; }
  .sidebar.open { transform: none; }
  .sidebar-inner { padding: 26px 24px; }
  .menu-close { display: block; }
  .course-identity { margin-top: 42px; }
  .scrim { position: fixed; z-index: 18; inset: 0; border: 0; background: rgba(10,21,27,.46); }
  .scrim.show { display: block; }
  .course-main { margin-left: 0; padding: 0; }
  .lesson-sheet { width: 100%; min-height: calc(100vh - 64px); padding: 44px 7vw 34px; }
  .intro-screen { padding-top: 12px; }
}
@media (max-width: 620px) {
  .lesson-sheet { padding-inline: 22px; }
  .intro-screen h1, .completion-screen h1 { font-size: 47px; }
  .lesson-content > h1 { font-size: 42px; }
  .lead { margin-block: 22px 30px; font-size: 18px; }
  .intro-facts { grid-template-columns: 1fr; }
  .intro-facts > div { min-height: 74px; padding: 13px 0; border-right: 0; border-bottom: 1px solid var(--line); }
  .intro-facts > div:last-child { border-bottom: 0; }
  .concept-card { grid-template-columns: 1fr; padding: 24px 20px; }
  .callout { grid-template-columns: 1fr; padding: 22px 18px; }
  .prompt-box, .example-panel, .built-prompt { align-items: stretch; flex-direction: column; }
  .prompt-box button, .example-panel button, .built-prompt button { width: 100%; }
  .choice-heading { align-items: flex-start; flex-direction: column; gap: 5px; }
  .use-choice { grid-template-columns: 28px 1fr; }
  .use-choice > b { grid-column: 2; }
  .custom-task { grid-template-columns: 1fr; gap: 18px; padding: 22px 18px; }
  .formula { grid-template-columns: 1fr; }
  .formula > i { height: 14px; text-align: center; }
  .prompt-builder { grid-template-columns: 1fr; }
  .comparison, .risk-scale { grid-template-columns: 1fr; }
  .comparison > span { transform: rotate(90deg); text-align: center; }
  .risk-scale > span { width: 1px; height: 18px; margin: 0 auto; }
  .takeaways { grid-template-columns: 1fr; }
  .lesson-footer { gap: 8px; }
  .previous-button, .next-button { min-height: 44px; padding-inline: 12px; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation: none !important; transition: none !important; }
}