:root {
  --ink: #171922;
  --paper: #f7f4ed;
  --paper-deep: #ece7db;
  --night: #12141d;
  --night-raised: #1a1e2a;
  --muted: #666b78;
  --line: #d9d2c4;
  --gold: #c99b22;
  --gold-dark: #8b6814;
  --blue: #365d83;
  --danger: #9a4141;
  --display: "Avenir Next", "Futura", "Helvetica Neue", system-ui, sans-serif;
  --body: "Iowan Old Style", "Palatino Linotype", "Book Antiqua", Georgia, serif;
  --mono: ui-monospace, "SF Mono", "JetBrains Mono", Menlo, monospace;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; background: var(--paper); }
body { margin: 0; color: var(--ink); background: var(--paper); font-family: var(--body); line-height: 1.65; -webkit-font-smoothing: antialiased; }
a { color: inherit; }
button, input { font: inherit; }
[hidden] { display: none !important; }

.skip-link { position: fixed; left: 16px; top: -80px; z-index: 20; padding: 10px 14px; color: var(--paper); background: var(--night); }
.skip-link:focus { top: 16px; }
.reading-progress { position: fixed; inset: 0 0 auto; height: 3px; z-index: 15; background: linear-gradient(90deg, var(--gold) var(--reading-progress, 0%), transparent 0); }

.learn-header { color: #eee9df; background: var(--night); border-bottom: 1px solid #292d39; }
.learn-nav { max-width: 1240px; margin: auto; min-height: 72px; padding: 0 28px; display: flex; align-items: center; justify-content: space-between; gap: 24px; }
.brand { display: inline-flex; align-items: center; gap: 9px; font: 650 16px/1 var(--display); letter-spacing: .16em; text-decoration: none; }
.brand span span { color: var(--gold); }
.learn-nav-links { display: flex; align-items: center; gap: 24px; font: 600 13px/1.3 var(--display); }
.learn-nav-links a { color: #b6bac7; text-decoration: none; }
.learn-nav-links a[aria-current="page"], .learn-nav-links a:hover { color: white; }
.sign-in-link { padding: 10px 15px; border: 1px solid #474d5d; border-radius: 4px; }

.learn-hero { color: #eee9df; background: var(--night); }
.learn-hero-inner { max-width: 1240px; margin: auto; padding: 78px 28px 82px; display: grid; grid-template-columns: minmax(0, 1.35fr) minmax(280px, .65fr); gap: 72px; align-items: end; }
.eyebrow, .section-label, .lesson-kicker, .scenario-label, .boundary-label { font: 700 11px/1.4 var(--mono); letter-spacing: .12em; text-transform: uppercase; }
.eyebrow, .lesson-kicker { color: var(--gold); }
.learn-hero h1 { max-width: 12ch; margin: 16px 0 22px; font: 550 clamp(44px, 6vw, 76px)/.98 var(--display); letter-spacing: -.045em; }
.learn-hero .lead { max-width: 700px; margin: 0; color: #b8bcc8; font: 19px/1.65 var(--display); }
.hero-promise { border-left: 1px solid #3a3f4c; padding-left: 30px; }
.hero-promise p { margin: 0 0 18px; color: #d8d4ca; font-size: 18px; }
.hero-promise ul { margin: 0; padding: 0; list-style: none; color: #9da3b2; font: 13px/1.9 var(--display); }
.hero-promise li::before { content: "—"; color: var(--gold); margin-right: 9px; }

.learn-shell { max-width: 1240px; margin: auto; padding: 54px 28px 96px; }
.learn-intro { display: grid; grid-template-columns: minmax(0, 1fr) minmax(310px, .45fr); gap: 54px; align-items: start; margin-bottom: 42px; }
.learn-intro h2 { max-width: 16ch; margin: 8px 0 12px; font: 600 35px/1.1 var(--display); letter-spacing: -.025em; }
.learn-intro p { max-width: 690px; color: var(--muted); font-size: 17px; }
.search-box { position: relative; }
.search-box label { display: block; margin-bottom: 8px; font: 650 12px/1.3 var(--display); }
.search-box input { width: 100%; padding: 14px 45px 14px 16px; color: var(--ink); background: #fffefa; border: 1px solid var(--line); border-radius: 5px; }
.search-box::after { content: "⌕"; position: absolute; right: 16px; bottom: 9px; color: var(--gold-dark); font: 24px/1 var(--display); }

.role-filters { display: flex; flex-wrap: wrap; gap: 8px; margin: 0 0 30px; }
.role-filter { padding: 9px 13px; color: #555a66; background: transparent; border: 1px solid var(--line); border-radius: 999px; cursor: pointer; font: 650 12px/1 var(--display); }
.role-filter.active { color: var(--paper); background: var(--night); border-color: var(--night); }
.role-filter:focus-visible, a:focus-visible, button:focus-visible, input:focus-visible { outline: 3px solid rgba(201,155,34,.45); outline-offset: 3px; }

.lesson-grid { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); border-top: 1px solid var(--line); border-left: 1px solid var(--line); }
.lesson-card { min-height: 282px; padding: 28px; background: #fbf9f3; border-right: 1px solid var(--line); border-bottom: 1px solid var(--line); display: flex; flex-direction: column; }
.lesson-card:hover { background: #fffdf7; }
.lesson-card .card-meta { display: flex; justify-content: space-between; gap: 16px; color: var(--muted); font: 650 10px/1.4 var(--mono); text-transform: uppercase; letter-spacing: .08em; }
.lesson-card h3 { margin: 28px 0 12px; font: 620 24px/1.15 var(--display); letter-spacing: -.02em; }
.lesson-card p { margin: 0 0 24px; color: var(--muted); font-size: 15px; }
.lesson-card a { margin-top: auto; color: var(--gold-dark); font: 700 12px/1.3 var(--display); text-decoration: none; }
.learning-empty { padding: 46px; text-align: center; border: 1px solid var(--line); background: #fbf9f3; }
.learning-empty button { color: var(--gold-dark); background: transparent; border: 0; text-decoration: underline; cursor: pointer; }

.lesson-reader { margin-top: 88px; }
.lesson { scroll-margin-top: 28px; }
.lesson-layout { display: grid; grid-template-columns: minmax(0, .34fr) minmax(0, 1fr); gap: 64px; }
.lesson-aside { position: sticky; top: 30px; align-self: start; padding-top: 6px; }
.lesson-aside dl { margin: 22px 0 0; padding-top: 18px; border-top: 1px solid var(--line); }
.lesson-aside div { margin-bottom: 15px; }
.lesson-aside dt { color: var(--muted); font: 650 10px/1.4 var(--mono); letter-spacing: .09em; text-transform: uppercase; }
.lesson-aside dd { margin: 3px 0 0; font: 650 13px/1.45 var(--display); }
.lesson-body { max-width: 790px; }
.lesson-body h1, .lesson-body h2 { margin: 10px 0 18px; font: 600 clamp(36px, 5vw, 58px)/1.02 var(--display); letter-spacing: -.04em; }
.lesson-deck { margin: 0 0 36px; color: var(--muted); font-size: 21px; }
.lesson-body h3 { margin: 46px 0 12px; font: 650 25px/1.2 var(--display); letter-spacing: -.015em; }
.lesson-body p, .lesson-body li { font-size: 17px; }
.scenario { margin: 40px 0; padding: 28px 30px; color: #e9e4da; background: var(--night-raised); border-left: 4px solid var(--gold); }
.scenario-label { color: var(--gold); }
.scenario h3 { margin: 8px 0 12px; color: white; }
.scenario p { margin: 0; color: #c4c7d0; }
.concept { display: grid; grid-template-columns: 130px 1fr; gap: 28px; margin: 36px 0; padding: 24px 0; border-block: 1px solid var(--line); }
.concept strong { font: 700 11px/1.4 var(--mono); letter-spacing: .09em; text-transform: uppercase; }
.concept p { margin: 0; }
.workflow { counter-reset: learning-step; margin: 22px 0 36px; padding: 0; list-style: none; }
.workflow li { counter-increment: learning-step; position: relative; padding: 0 0 23px 48px; }
.workflow li::before { content: counter(learning-step); position: absolute; left: 0; top: 1px; width: 28px; height: 28px; border: 1px solid var(--gold-dark); border-radius: 50%; display: grid; place-items: center; color: var(--gold-dark); font: 700 11px/1 var(--mono); }
.boundary { margin: 42px 0; padding: 24px 28px; background: var(--paper-deep); border: 1px solid var(--line); }
.boundary-label { color: var(--danger); }
.boundary p { margin: 6px 0 0; }
.lesson-actions { display: flex; flex-wrap: wrap; gap: 12px; margin-top: 36px; }
.lesson-action { min-height: 42px; padding: 11px 17px; display: inline-flex; align-items: center; justify-content: center; color: white; background: var(--night); border: 1px solid var(--night); border-radius: 4px; font: 700 12px/1.2 var(--display); text-align: center; text-decoration: none; }
.lesson-action.secondary { color: var(--ink); background: transparent; border-color: var(--line); }
.copy-lesson { padding: 0; color: var(--gold-dark); background: transparent; border: 0; cursor: pointer; font: 700 12px/1.3 var(--display); }

.available-boundary { margin-top: 96px; padding: 34px; color: #d8d4ca; background: var(--night); display: grid; grid-template-columns: .55fr 1fr; gap: 40px; }
.available-boundary h2 { margin: 8px 0 0; color: white; font: 600 30px/1.15 var(--display); }
.available-boundary p, .available-boundary li { color: #aeb2be; font: 14px/1.65 var(--display); }
.available-boundary ul { columns: 2; margin: 0; padding-left: 18px; }

.learn-footer { color: #a7acb8; background: #0e1017; }
.learn-footer-inner { max-width: 1240px; margin: auto; padding: 38px 28px; display: flex; justify-content: space-between; gap: 30px; font: 12px/1.7 var(--display); }
.learn-footer a { color: #ded9cf; }

.customer-guide-banner { padding: 14px 28px; color: #d8d4ca; background: #202431; text-align: center; font: 12px/1.5 var(--display); }
.customer-guide-banner strong { color: var(--gold); }
.guide-checklist { margin: 24px 0 0; padding: 0; list-style: none; }
.guide-checklist li { position: relative; padding-left: 28px; margin: 9px 0; }
.guide-checklist li::before { content: "✓"; position: absolute; left: 0; color: var(--gold-dark); font-family: var(--display); }
.expected-state { margin: 24px 0; padding: 18px 22px; border-left: 3px solid var(--blue); background: rgba(54,93,131,.08); }

@media (max-width: 900px) {
  .learn-hero-inner, .learn-intro, .lesson-layout, .available-boundary { grid-template-columns: 1fr; }
  .hero-promise { border-left: 0; border-top: 1px solid #3a3f4c; padding: 26px 0 0; }
  .lesson-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .lesson-aside { position: static; }
}

@media (max-width: 620px) {
  .learn-nav { padding: 0 18px; }
  .learn-nav-links a:not(.sign-in-link) { display: none; }
  .learn-hero-inner { padding: 58px 20px 62px; }
  .learn-hero h1 { font-size: 44px; }
  .learn-shell { padding: 42px 20px 72px; }
  .lesson-grid { grid-template-columns: 1fr; }
  .lesson-card { min-height: 0; }
  .concept { grid-template-columns: 1fr; gap: 8px; }
  .available-boundary ul { columns: 1; }
  .learn-footer-inner { flex-direction: column; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { animation-duration: .01ms !important; animation-iteration-count: 1 !important; transition-duration: .01ms !important; }
}