:root {
  color-scheme: light;
  --ink: #14263d;
  --muted: #536476;
  --paper: #f5f7fa;
  --card: #ffffff;
  --accent: #168a86;
  --accent-dark: #0c5f5d;
  --line: #d8e0e8;
}

* { box-sizing: border-box; }

[hidden] { display: none !important; }

body {
  margin: 0;
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  color: var(--ink);
  background: var(--paper);
  line-height: 1.6;
}

.book-banner { position: sticky; top: 0; z-index: 10; display: flex; justify-content: center; align-items: center; gap: 1rem; padding: 0.65rem 1.25rem; background: var(--accent-dark); color: white; font-size: 0.88rem; }
.book-banner p { margin: 0; text-align: center; }
.banner-actions { display: flex; align-items: center; gap: 0.7rem; flex: 0 0 auto; }
.banner-actions a { color: white; font-weight: 800; white-space: nowrap; }
.banner-actions button { border: 1px solid rgb(255 255 255 / 65%); border-radius: 50%; width: 1.6rem; height: 1.6rem; padding: 0; background: transparent; color: white; font-size: 1.15rem; line-height: 1; cursor: pointer; }
.banner-actions button:hover { background: rgb(255 255 255 / 16%); }

.site-header, main, .site-footer { max-width: 1120px; margin: 0 auto; }
.site-header { display: flex; justify-content: space-between; gap: 1rem; align-items: baseline; padding: 1.5rem 1.25rem; }
.brand { color: var(--ink); font-size: 1.1rem; font-weight: 800; text-decoration: none; letter-spacing: -0.02em; }
.tagline { color: var(--muted); font-size: 0.92rem; }
.site-nav { display: flex; gap: 1.25rem; }
.site-nav a { color: var(--muted); font-size: 0.9rem; font-weight: 800; text-decoration: none; }
.site-nav a:hover, .site-nav a[aria-current="page"] { color: var(--accent-dark); }

.hero { padding: 6rem 1.25rem 5rem; max-width: 820px; }
.hero-short { padding-top: 5rem; padding-bottom: 4rem; }
.eyebrow { color: var(--accent-dark); font-size: 0.78rem; font-weight: 800; letter-spacing: 0.12em; text-transform: uppercase; }
h1, h2, h3 { line-height: 1.15; letter-spacing: -0.035em; }
h1 { font-size: clamp(2.5rem, 6vw, 5.2rem); margin: 0.5rem 0 1.25rem; }
h2 { font-size: clamp(2rem, 4vw, 3.4rem); margin: 0.5rem 0 1rem; }
h3 { font-size: 1.45rem; margin: 0.6rem 0; }
.intro { color: var(--muted); font-size: 1.2rem; max-width: 680px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 0.75rem; }
.button { display: inline-block; border: 0; border-radius: 999px; background: var(--accent); color: white; padding: 0.8rem 1.25rem; font-weight: 700; text-decoration: none; margin-top: 1rem; }
.button:hover { background: var(--accent-dark); }
.button.outline { background: transparent; color: var(--ink); border: 1px solid var(--line); }
.button.outline:hover { background: white; border-color: var(--accent); }
.button.secondary { background: var(--ink); font-size: 0.85rem; }
.button:disabled { cursor: not-allowed; opacity: 0.65; }

.book-promo { display: grid; grid-template-columns: 220px 1fr; gap: 3rem; align-items: center; margin: 0 1.25rem 4rem; padding: 3rem; border: 1px solid var(--line); border-radius: 1.25rem; background: var(--card); box-shadow: 0 12px 30px rgb(20 38 61 / 7%); }
.book-promo.compact { grid-template-columns: 160px 1fr; gap: 2rem; padding: 2rem 2.25rem; margin-bottom: 3rem; }
.book-promo.compact .book-cover { width: min(100%, 160px); }
.book-promo.compact h2 { font-size: clamp(1.8rem, 3vw, 2.5rem); }
.book-cover-wrap { display: flex; justify-content: center; }
.book-cover { display: block; width: min(100%, 220px); border-radius: 0.35rem; box-shadow: 0 18px 28px rgb(20 38 61 / 22%); }
.book-copy { max-width: 680px; }
.book-lede { color: var(--accent-dark); font-size: 1.25rem; font-weight: 700; }
.book-points { padding-left: 1.2rem; color: var(--muted); }

.course-section { display: grid; grid-template-columns: 1fr 1fr; gap: 3rem; padding: 4rem 1.25rem; border-top: 1px solid var(--line); }
.course-section > div:first-child { max-width: 540px; }
.course-card { background: var(--card); border: 1px solid var(--line); border-radius: 1.25rem; padding: 2rem; box-shadow: 0 12px 30px rgb(20 38 61 / 7%); }
.card-label { color: var(--accent-dark); font-size: 0.78rem; font-weight: 800; letter-spacing: 0.1em; text-transform: uppercase; }
.course-book-note { color: var(--muted); font-size: 0.95rem; }
.course-book-note a { color: var(--accent-dark); font-weight: 800; }
.auth-panel { margin-top: 1.5rem; padding-top: 1.5rem; border-top: 1px solid var(--line); }
.auth-panel h4 { margin: 0 0 0.35rem; font-size: 1.05rem; }
.auth-panel p { color: var(--muted); font-size: 0.92rem; }
.auth-panel form { display: grid; gap: 0.45rem; margin-top: 1rem; }
.auth-panel label { font-size: 0.85rem; font-weight: 700; }
.auth-panel input { width: 100%; border: 1px solid var(--line); border-radius: 0.5rem; padding: 0.75rem; font: inherit; color: var(--ink); }
.auth-panel .button { justify-self: start; margin-top: 0.35rem; }
.auth-message { min-height: 1.5rem; font-weight: 700; }
.signed-in-dashboard { margin-top: 1.25rem; }
.dashboard-heading { display: flex; justify-content: space-between; gap: 1rem; align-items: flex-start; }
.dashboard-actions { display: flex; align-items: center; gap: 0.9rem; flex: 0 0 auto; }
.dashboard-heading h4 { margin: 0.15rem 0 0; font-size: 1.35rem; }
.dashboard-heading .eyebrow { margin: 0; }
.profile-email { margin: 0.2rem 0 0; }
.text-button { border: 0; background: transparent; color: var(--accent-dark); font: inherit; font-weight: 800; cursor: pointer; padding: 0.2rem 0; }
.profile-form { margin-top: 1.25rem; }
.profile-hint { margin: 0 0 0.7rem; color: var(--muted); font-size: 0.9rem; }
.profile-form-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.65rem; }
.profile-form-row { display: flex; gap: 0.65rem; align-items: center; }
.profile-form-row input { flex: 1; }
.profile-form-row .button { margin-top: 0; white-space: nowrap; }
.profile-form > .button { margin-top: 0.8rem; }
.course-placeholder { margin-top: 1.5rem; padding: 1.15rem; border: 1px dashed var(--accent); border-radius: 0.75rem; background: #f0fbfa; }
.course-placeholder h5 { margin: 0.45rem 0 0.25rem; font-size: 1rem; }
.course-placeholder p { margin: 0; }
.feature-strip { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1rem; margin: 0 1.25rem 3rem; }
.feature-card { padding: 1.35rem; border-top: 3px solid var(--accent); background: var(--card); }
.feature-card h3 { font-size: 1.1rem; margin: 0.5rem 0 0.35rem; }
.feature-card p { margin: 0; color: var(--muted); font-size: 0.92rem; }
.home-cta { margin: 0 1.25rem 4rem; padding: 2.5rem; border-radius: 1.25rem; background: var(--ink); color: white; }
.home-cta .eyebrow { color: #9be4df; }
.home-cta h2 { max-width: 560px; margin-bottom: 0.75rem; }
.course-page-heading { padding: 2.75rem 1.25rem 1.5rem; max-width: 760px; }
.course-page-heading h1 { font-size: clamp(2.35rem, 4.4vw, 3.75rem); margin-bottom: 0.75rem; }
.course-page-heading .intro { font-size: 1.08rem; }
.course-layout { display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(320px, 0.85fr); gap: 2rem; padding: 1rem 1.25rem 4rem; }
.course-outline { display: grid; gap: 1rem; align-content: start; }
.course-outline > .eyebrow { margin: 0.5rem 0 0; }
.lesson-card { padding: 1.35rem 1.5rem; border: 1px solid var(--line); border-radius: 0.9rem; background: var(--card); }
.lesson-card-current { border-color: var(--accent); box-shadow: 0 10px 22px rgb(20 38 61 / 7%); }
.lesson-card h2 { font-size: 1.35rem; margin: 0.45rem 0 0.25rem; }
.lesson-card p { margin: 0 0 0.75rem; color: var(--muted); }
.lesson-meta { color: var(--muted); font-size: 0.8rem; font-weight: 700; }
.auth-card { align-self: start; position: sticky; top: 4.5rem; }
.auth-card .auth-panel { margin-top: 0; padding-top: 0; border-top: 0; }
.auth-card .auth-panel h2 { font-size: 1.55rem; margin: 0 0 0.5rem; }
.signed-in-note { margin-top: 1.25rem; padding-top: 1rem; border-top: 1px solid var(--line); }
.principles { margin: 2rem 1.25rem 5rem; border-radius: 1.25rem; padding: 3rem; background: var(--ink); color: white; }
.principles .eyebrow { color: #9be4df; }
.site-footer { border-top: 1px solid var(--line); color: var(--muted); padding: 1.5rem 1.25rem 3rem; font-size: 0.9rem; }

@media (max-width: 720px) {
  .book-banner { align-items: flex-start; gap: 0.65rem; padding: 0.65rem 0.8rem; font-size: 0.78rem; }
  .banner-actions { gap: 0.45rem; }
  .site-header { display: block; }
  .site-nav { margin-top: 0.75rem; }
  .tagline { display: block; margin-top: 0.35rem; }
  .hero { padding-top: 4rem; }
  .book-promo { grid-template-columns: 1fr; gap: 2rem; padding: 2rem; }
  .book-promo.compact { grid-template-columns: 1fr; }
  .feature-strip { grid-template-columns: 1fr; }
  .course-section { grid-template-columns: 1fr; gap: 1.5rem; }
  .course-page-heading { padding-top: 3rem; }
  .course-layout { grid-template-columns: 1fr; }
  .auth-card { position: static; }
  .dashboard-actions { gap: 0.65rem; }
  .profile-form-row { display: grid; }
  .profile-form-row .button { justify-self: start; }
  .profile-form-grid { grid-template-columns: 1fr; }
  .principles { margin-top: 0; padding: 2rem; }
}