:root {
  color-scheme: light;
  --ink: #27313d;
  --muted: #6d7988;
  --quiet: #9aa5b2;
  --line: #d9e0e8;
  --line-strong: #c7d0db;
  --paper: #ffffff;
  --canvas: #f3f5f7;
  --canvas-deep: #e9edf2;
  --blue: #315f9c;
  --blue-soft: #e9f0fb;
  --green: #31765a;
  --green-soft: #eaf5ee;
  --red: #a24a48;
  --red-soft: #faeeee;
  --amber: #8d681e;
  --amber-soft: #fbf4df;
  --purple: #6e4a9c;
  --purple-soft: #f0e9fb;
  --shadow: 0 12px 30px rgba(48, 62, 78, .06);
  font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  min-width: 320px;
  background: var(--canvas);
  color: var(--ink);
  font-size: 14px;
  line-height: 1.45;
}

button, a { font: inherit; }
button { cursor: pointer; }
button:focus-visible, a:focus-visible { outline: 3px solid rgba(49, 95, 156, .32); outline-offset: 2px; }

.app-shell { min-height: 100vh; }
.loading-state { display: grid; min-height: 60vh; place-items: center; gap: 10px; justify-items: center; color: var(--muted); }

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
  max-width: 1440px;
  margin: 0 auto;
  padding: 28px 42px 20px;
}

.brand-lockup { display: flex; align-items: center; gap: 16px; }
.brand-lockup h1 { margin: 0; font-size: 18px; letter-spacing: -.02em; font-weight: 680; }
.brand-lockup p { margin: 2px 0 0; color: var(--muted); font-size: 12px; }

.eyebrow { color: var(--ink); font-size: 12px; font-weight: 800; letter-spacing: .2em; line-height: 1; }
.eyebrow span { color: var(--blue); }

.topbar-actions { color: var(--muted); font-size: 12px; }
.source-badge { display: inline-flex; align-items: center; gap: 7px; color: var(--blue); font-weight: 700; }
.status-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--blue); box-shadow: 0 0 0 3px var(--blue-soft); }

.main-nav {
  display: flex;
  gap: 4px;
  max-width: 1440px;
  margin: 0 auto;
  padding: 0 42px;
  border-bottom: 1px solid var(--line);
}

.nav-tab {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 12px 18px 13px;
  border: 0;
  border-bottom: 2px solid transparent;
  background: transparent;
  color: var(--muted);
  font-weight: 680;
}
.nav-tab:hover, .nav-tab.is-active { color: var(--ink); }
.nav-tab.is-active { border-bottom-color: var(--blue); }
.nav-index { color: var(--quiet); font-size: 10px; letter-spacing: .1em; }

.workspace { max-width: 1440px; margin: 0 auto; padding: 44px 42px 72px; }
.site-footer { display: flex; justify-content: space-between; max-width: 1440px; margin: 0 auto; padding: 0 42px 28px; color: var(--quiet); font-size: 11px; letter-spacing: .02em; }

.page-heading { align-items: flex-end; margin-bottom: 26px; display: flex; justify-content: space-between; gap: 16px; }
.page-heading > div:first-child { max-width: 760px; }
.section-kicker, .panel-kicker { display: block; color: var(--blue); font-size: 10px; font-weight: 800; letter-spacing: .16em; text-transform: uppercase; }
.page-heading h2 { margin: 7px 0 7px; font-size: clamp(24px, 3vw, 34px); line-height: 1.1; letter-spacing: -.04em; font-weight: 720; }
.page-heading p { max-width: 680px; margin: 0; color: var(--muted); font-size: 14px; }

.panel { border: 1px solid var(--line); border-radius: 10px; background: var(--paper); box-shadow: var(--shadow); }
.panel-heading { display: flex; align-items: flex-start; justify-content: space-between; gap: 16px; padding: 20px 22px 16px; border-bottom: 1px solid var(--line); }
.panel-heading h3 { margin: 5px 0 0; font-size: 15px; letter-spacing: -.015em; }
.small-note { color: var(--quiet); font-size: 11px; }

/* ── lens sidebar filter (Tab 1) ──────────────────────────────────────── */
.lenses-layout { display: grid; grid-template-columns: 240px minmax(0, 1fr); align-items: start; gap: 28px; }
.lens-sidebar { position: sticky; top: 20px; padding: 16px 14px; border: 1px solid var(--line); border-radius: 10px; background: var(--paper); box-shadow: var(--shadow); }
.lens-sidebar-heading { display: block; margin-bottom: 10px; padding: 0 4px; color: var(--quiet); font-size: 10px; font-weight: 800; letter-spacing: .12em; text-transform: uppercase; }
.lens-sidebar-tree, .lens-sidebar-types { list-style: none; margin: 0; padding: 0; }
.lens-sidebar-item + .lens-sidebar-item { margin-top: 10px; }
.lens-sidebar-lens { display: block; width: 100%; padding: 8px 10px; border: 0; border-radius: 7px; background: transparent; color: var(--ink); font-size: 13px; font-weight: 700; text-align: left; }
.lens-sidebar-lens:hover { background: var(--canvas); }
.lens-sidebar-lens.is-active { background: var(--blue-soft); color: var(--blue); }
.lens-sidebar-lens.is-parent-active { color: var(--blue); }
.lens-sidebar-types { margin: 2px 0 0 10px; padding-left: 10px; border-left: 1px solid var(--line); }
.lens-sidebar-type { display: block; width: 100%; margin-top: 2px; padding: 6px 9px; border: 0; border-radius: 6px; background: transparent; color: var(--muted); font-size: 12px; text-align: left; }
.lens-sidebar-type:hover { background: var(--canvas); color: var(--ink); }
.lens-sidebar-type.is-active { background: var(--blue); color: #fff; font-weight: 650; }
.lens-sidebar-lens.is-planned, .lens-sidebar-type.is-planned { color: var(--quiet); cursor: default; font-style: italic; }
.lens-sidebar-lens.is-planned:hover, .lens-sidebar-type.is-planned:hover { background: transparent; color: var(--quiet); }
.lenses-main { min-width: 0; }
.lens-collapsed-note { padding: 16px 26px 22px; color: var(--quiet); font-size: 12px; }

/* ── lens blocks (Tab 1) ───────────────────────────────────────────── */
.lens-block { margin-bottom: 48px; scroll-margin-top: 16px; }
.lens-block.is-selected { box-shadow: 0 0 0 2px var(--blue), var(--shadow); }
.lens-block-header { padding: 24px 26px 20px; border-bottom: 1px solid var(--line); }
.lens-index { display: block; color: var(--blue); font-size: 10px; font-weight: 800; letter-spacing: .16em; text-transform: uppercase; margin-bottom: 6px; }
.lens-block-header h2 { margin: 0 0 4px; font-size: 28px; letter-spacing: -.03em; }
.lens-types { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 10px; }
.lens-type-chip { border-radius: 999px; padding: 4px 9px; background: var(--blue-soft); color: var(--blue); font-size: 10px; font-weight: 750; letter-spacing: .02em; }
.lens-type-chip.is-excluded { background: var(--red-soft); color: var(--red); }

.lens-descriptions { display: grid; grid-template-columns: 1fr 1fr; gap: 0; border-bottom: 1px solid var(--line); }
.lens-description-col { padding: 20px 26px; }
.lens-description-col + .lens-description-col { border-left: 1px solid var(--line); }
.lens-description-col span.label { display: block; color: var(--quiet); font-size: 10px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; margin-bottom: 8px; }
.lens-description-col p { margin: 0; color: var(--ink); font-size: 14px; line-height: 1.6; }
.lens-description-col.plain-english { background: #fbfdff; }
.lens-description-col.plain-english p { font-size: 15px; }

.lens-references { padding: 14px 26px 18px; background: var(--canvas); }
.lens-references-label { display: block; color: var(--quiet); font-size: 10px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; margin-bottom: 8px; }
.lens-references ul { margin: 0; padding: 0; list-style: none; display: grid; gap: 6px; }
.lens-references li { font-size: 12px; color: var(--muted); line-height: 1.5; }
.lens-references li strong { color: var(--ink); font-weight: 650; }
.lens-references code { background: var(--canvas-deep); padding: 1px 5px; border-radius: 4px; font-size: 11px; }

.example-group { padding: 22px 26px 26px; border-top: 1px solid var(--line); scroll-margin-top: 16px; }
.example-group-heading { display: flex; align-items: baseline; gap: 10px; margin-bottom: 14px; }
.example-group-heading h4 { margin: 0; font-size: 15px; letter-spacing: -.01em; }
.example-group-heading .exercise-type-badge { border-radius: 999px; padding: 3px 9px; background: var(--purple-soft); color: var(--purple); font-size: 10px; font-weight: 780; letter-spacing: .04em; text-transform: uppercase; }
.example-group-heading .small-note { margin-left: auto; }

.card-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(427px, 1fr)); align-items: start; gap: 16px; }

.example-card { border: 1px solid var(--line); border-radius: 10px; background: var(--paper); box-shadow: var(--shadow); overflow: hidden; }
.example-card-header { padding: 14px 16px 12px; border-bottom: 1px solid var(--line); }
.example-card-eyebrow { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-bottom: 8px; color: var(--quiet); font-size: 10px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.example-card-eyebrow .complicator-tag { color: var(--blue); }
.example-card h5 { margin: 0 0 4px; font-size: 13px; font-weight: 700; color: var(--ink); }
.example-card .expression { font: 650 13px/1.4 ui-monospace, SFMono-Regular, Menlo, monospace; color: var(--muted); }
.example-card-source { padding: 10px 16px; border-top: 1px solid var(--line); background: #fafbfc; color: var(--quiet); font-size: 10px; line-height: 1.5; }
.example-card-source a { color: var(--blue); }
.status-badge { display: inline-block; border-radius: 999px; padding: 2px 7px; background: var(--amber-soft); color: var(--amber); font-size: 9px; font-weight: 800; letter-spacing: .04em; text-transform: uppercase; }

.exercise-text-card { padding: 14px 16px; }
.exercise-text-card .stem { margin: 0 0 10px; color: var(--ink); font-size: 13px; line-height: 1.55; }
.exercise-text-card ul.choices { margin: 0; padding: 0; list-style: none; display: grid; gap: 6px; }
.exercise-text-card ul.choices li { padding: 7px 10px; border: 1px solid var(--line); border-radius: 7px; font-size: 12px; color: var(--muted); }
.exercise-text-card ul.choices li.is-correct { border-color: #b7d8c4; background: var(--green-soft); color: var(--green); font-weight: 650; }
.exercise-text-card .answer-note { margin: 10px 0 0; padding: 8px 10px; border-radius: 7px; background: var(--canvas); color: var(--muted); font-size: 11px; line-height: 1.5; }

.preview-stage { display: flex; width: 393px; max-width: 100%; min-height: 852px; margin: 0 auto; align-items: flex-start; justify-content: center; overflow: hidden; }
.preview-stage > .heph-preview-host { flex: 0 0 393px; width: 393px; height: 852px; max-width: 393px; }
.preview-loading, .preview-error, .preview-fallback { display: grid; width: 100%; min-height: 240px; padding: 20px; align-content: center; justify-items: center; gap: 6px; text-align: center; color: var(--muted); font-size: 12px; }
.preview-fallback strong, .preview-error strong { color: var(--ink); font-size: 12px; }
.svg-preview { max-width: 100%; }

.no-example-note { padding: 18px; border: 1px dashed var(--line-strong); border-radius: 10px; color: var(--muted); font-size: 12px; text-align: center; background: #fafbfc; }

/* ── skills (Tab 2) ────────────────────────────────────────────────── */
.overview-strip { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); margin-bottom: 26px; border: 1px solid var(--line); border-radius: 10px; background: var(--paper); box-shadow: var(--shadow); }
.overview-strip > div { min-height: 78px; padding: 15px 18px; border-right: 1px solid var(--line); }
.overview-strip > div:last-child { border-right: 0; }
.overview-strip span { display: block; color: var(--muted); font-size: 11px; }
.overview-strip strong { display: block; margin-top: 3px; color: var(--ink); font-size: 23px; letter-spacing: -.04em; }

.complicator-block { margin-bottom: 22px; }
.complicator-block-header { padding: 16px 20px; }
.complicator-block-header .course-tag { color: var(--blue); font-size: 10px; font-weight: 800; letter-spacing: .1em; text-transform: uppercase; }
.complicator-block-header .expression { display: block; margin: 6px 0 4px; font: 700 20px/1.3 ui-monospace, SFMono-Regular, Menlo, monospace; color: var(--ink); }
.complicator-block-header .complicator-name { margin: 0; color: var(--muted); font-size: 13px; line-height: 1.5; }
.complicator-block-header .complicator-id { display: block; margin-top: 8px; color: var(--quiet); font: 500 10px/1.4 ui-monospace, SFMono-Regular, Menlo, monospace; }

.skill-list { padding: 6px 0; }
.skill-row { display: flex; align-items: flex-start; justify-content: space-between; gap: 18px; padding: 13px 20px; border-top: 1px solid #edf0f3; }
.skill-row:first-child { border-top: 0; }
.skill-copy { display: flex; align-items: flex-start; gap: 10px; min-width: 0; }
.skill-marker { flex: 0 0 auto; width: 7px; height: 7px; margin-top: 7px; border: 2px solid var(--blue); border-radius: 50%; background: var(--paper); }
.skill-copy strong { display: block; font-size: 13px; font-weight: 680; }
.skill-copy p { margin: 3px 0 0; color: var(--muted); font-size: 12px; }
.skill-meta { flex: 0 0 auto; text-align: right; color: var(--quiet); font-size: 10px; line-height: 1.5; }

.empty-state { padding: 40px; text-align: center; color: var(--muted); }

@media (max-width: 900px) {
  .lens-descriptions { grid-template-columns: 1fr; }
  .lens-description-col + .lens-description-col { border-left: 0; border-top: 1px solid var(--line); }
  .overview-strip { grid-template-columns: 1fr 1fr; }
  .card-grid { grid-template-columns: 1fr; }
  .lenses-layout { grid-template-columns: 1fr; }
  .lens-sidebar { position: static; }
}