/* ── Reset & base ──────────────────────────────────────────── */
*, *::before, *::after { margin: 0; padding: 0; box-sizing: border-box; }

/*
 * ── Design tokens ─────────────────────────────────────────────
 *
 *  Colors
 *  bg:                 #040714
 *  surface-1 (cards):  rgba(255,255,255,.03)
 *  surface-2 (hover):  rgba(255,255,255,.06)
 *  border-subtle:      rgba(255,255,255,.07)
 *  border:             rgba(255,255,255,.1)
 *  border-strong:      rgba(255,255,255,.22)
 *  blue accent:        #0063e5
 *  blue accent bright: #0080ff
 *  text primary:       #f9f9f9
 *  text secondary:     #cacaca
 *  text muted:         rgba(255,255,255,.55)
 *  header gradient:    in oklch 135deg, #B015B0 0%, #3D0080 50%, #040714 100%
 *
 *  Typography scale (rem)
 *  --text-xs: 0.75    --text-sm: 0.875   --text-base: 1
 *  --text-lg: 1.125   --text-xl: 1.25    --text-2xl: 1.5
 *  font stack: 'Avenir Next', -apple-system, BlinkMacSystemFont,
 *              'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif
 *
 *  Spacing scale (4px grid)
 *  --space-1: 4px   --space-2: 8px   --space-3: 12px   --space-4: 16px
 *  --space-6: 24px  --space-8: 32px
 *
 *  Radii
 *  --radius-sm: 6px   --radius: 10px   --radius-lg: 15px
 *
 *  Easing
 *  --ease-snap: cubic-bezier(0.34, 1.56, 0.64, 1)  (spring/overshoot)
 *  --dur-fast: 120ms   --dur: 200ms
 *
 *  UI primitives
 *  --control-height: 44px   (touch minimum)
 *  --control-height-sm: 36px
 *  --z-sticky-header: 200   --z-modal: 400   --z-toast: 500
 */

:root {
  --bg: #040714;
  --surface-1: rgba(255,255,255,.03);
  --surface-2: rgba(255,255,255,.06);
  --surface-toast: #1a1730;
  --border-subtle: rgba(255,255,255,.07);
  --border: rgba(255,255,255,.1);
  --border-strong: rgba(255,255,255,.22);
  --text-primary: #f9f9f9;
  --text-secondary: #cacaca;
  --text-muted: rgba(255,255,255,.55);
  --accent: #0063e5;
  --accent-bright: #0080ff;
  --danger: #e11d48;
  --danger-hover: #f43f5e;
  --font: 'Avenir Next', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  --text-xs: 0.75rem; --text-sm: 0.875rem; --text-base: 1rem;
  --text-lg: 1.125rem; --text-xl: 1.25rem; --text-2xl: 1.5rem;
  --space-1: 4px; --space-2: 8px; --space-3: 12px; --space-4: 16px;
  --space-6: 24px; --space-8: 32px;
  --radius-sm: 6px; --radius: 10px; --radius-lg: 15px;
  --ease-snap: cubic-bezier(0.34, 1.56, 0.64, 1);
  --dur-fast: 120ms; --dur: 200ms;
  --control-height: 44px;
  --control-height-sm: 36px;
  --shadow-card: 0 12px 28px rgba(15, 23, 42, 0.5);
  --shadow-modal: 0 24px 48px rgba(2, 6, 23, 0.58);
  --z-sticky-header: 200;
  --z-modal: 400;
  --z-toast: 500;
}

html { height: 100%; }
body {
  font-family: var(--font);
  background: var(--bg);
  min-height: 100%;
  color: var(--text-primary);
  display: flex; flex-direction: column;
}

body.modal-open {
  overflow: hidden;
}

main#main {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-height: 0;
  width: 100%;
}

/* ── Layout ────────────────────────────────────────────────── */
/*
 * GOTCHA: body { display:flex; flex-direction:column } + margin: 0 auto
 * on a child collapses its width — always pair with width: 100%.
 *
 * GOTCHA: External images (YouTube ggpht, Gravatar, etc.) may block loading
 * when the Referer header points to localhost or an unknown origin. Fix:
 * 1. Add <meta name="referrer" content="no-referrer"> in <head> (global)
 * 2. Or add referrerpolicy="no-referrer" on each <img> tag
 */
.container {
  max-width: 900px;
  width: 100%;
  margin: 0 auto;
  padding: var(--space-6);
  flex: 1;
}

/* Vertical rhythm: use inside .container or nested regions */
.stack {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}
.stack--tight { gap: var(--space-4); }
.stack--loose { gap: var(--space-8); }

/* Page section: title row + body (replaces “card everything” for grouping) */
.section {
  display: flex;
  flex-direction: column;
  gap: var(--space-4);
}
.section__header {
  display: flex;
  flex-wrap: wrap;
  align-items: flex-end;
  justify-content: space-between;
  gap: var(--space-4);
}
.section__titles {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  min-width: 0;
}
.section__title {
  font-size: var(--text-xl);
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--text-primary);
}
.section__lead {
  font-size: var(--text-sm);
  color: var(--text-muted);
  line-height: 1.45;
  max-width: 52ch;
}
.section__lead code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  font-size: 0.92em;
  color: var(--text-secondary);
}
.stack > .card { margin-bottom: 0; }
.toolbar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
}

/* ── Header ────────────────────────────────────────────────── */
.header-bar {
  background: linear-gradient(in oklch 135deg, #B015B0 0%, #3D0080 50%, #040714 100%);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
  padding: 0 var(--space-6);
  height: 68px;
  position: sticky;
  top: 0;
  z-index: var(--z-sticky-header);
  display: flex;
  align-items: center;
}

.header-logo { display: flex; align-items: center; gap: 10px; flex-shrink: 0; }

.header-logo-img {
  height: 36px; width: auto; flex-shrink: 0;
  filter: brightness(0) invert(1);
  transition: transform 0.3s var(--ease-snap);
  display: block;
}
.header-logo-img:hover { transform: scale(1.14) rotate(-9deg); }

.header-title-link { text-decoration: none; color: inherit; }
.header-logo h1 { font-size: 1.2em; font-weight: 600; color: var(--text-primary); letter-spacing: .5px; }
.header-subtitle { font-size: .82em; color: rgba(255,255,255,.72); font-weight: 500; margin-top: 3px; }

/* ── Nav & Auth ────────────────────────────────────────────── */
/*
 * THREE PATTERNS:
 *   A) No nav, no auth → margin-left: auto on .header-home
 *   B) Auth only       → margin-left: auto on .auth-toggle, margin-left: 8px on .header-home
 *   C) Nav + auth      → margin-left: auto on <nav>, margin-left: 5px on .header-home
 */
nav {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}

.header-home {
  display: flex; align-items: center; justify-content: center;
  margin-left: auto;
  min-width: var(--control-height);
  min-height: var(--control-height);
  padding: var(--space-2);
  color: rgba(255,255,255,0.9); text-decoration: none;
  border-radius: var(--radius-sm);
  transition: color var(--dur), background var(--dur);
  flex-shrink: 0;
}
.header-home:hover { color: #fff; background: rgba(255,255,255,0.12); }
.header-home svg { width: 34px; height: 34px; display: block; }

/* ── Buttons (canonical) ─────────────────────────────────────
 * Use .btn + a variant. Aliases: .nav-link = toolbar ghost; .auth-* map below.
 */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-2);
  min-height: var(--control-height);
  padding: 0 var(--space-4);
  border-radius: var(--radius-sm);
  font-family: inherit;
  font-size: var(--text-sm);
  font-weight: 600;
  line-height: 1.2;
  text-decoration: none;
  cursor: pointer;
  border: 1px solid transparent;
  background: transparent;
  color: var(--text-primary);
  transition:
    background-color var(--dur),
    color var(--dur),
    border-color var(--dur),
    box-shadow var(--dur),
    transform var(--dur-fast);
  -webkit-tap-highlight-color: transparent;
}
.btn:disabled,
.btn[aria-disabled="true"] {
  opacity: 0.45;
  cursor: not-allowed;
  pointer-events: none;
}
.btn--sm {
  min-height: var(--control-height-sm);
  padding: 0 var(--space-3);
  font-size: var(--text-xs);
}
.btn--block { width: 100%; }
.btn--icon {
  min-width: var(--control-height);
  padding: 0;
}
.btn--primary {
  background: var(--accent);
  color: #fff;
  border-color: transparent;
}
.btn--primary:hover { background: var(--accent-bright); }
.btn--secondary {
  background: var(--surface-2);
  color: var(--text-primary);
  border-color: var(--border-strong);
}
.btn--secondary:hover {
  background: rgba(255, 255, 255, 0.1);
}
.btn--ghost {
  background: transparent;
  color: rgba(255,255,255,0.92);
  border-color: rgba(255,255,255,0.18);
}
.btn--ghost:hover {
  background: rgba(255,255,255,0.1);
  color: #fff;
}
.btn--danger {
  background: var(--danger);
  color: #fff;
  border-color: transparent;
}
.btn--danger:hover { background: var(--danger-hover); }

/* Toolbar ghost (header nav) — same as .btn.btn--ghost.btn--sm */
.nav-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: var(--control-height);
  padding: 0 var(--space-3);
  border: 1px solid rgba(255,255,255,0.18);
  border-radius: var(--radius-sm);
  background: transparent;
  color: rgba(255,255,255,0.92);
  cursor: pointer;
  font-family: inherit;
  font-size: var(--text-sm);
  font-weight: 600;
  transition: background-color var(--dur), color var(--dur), border-color var(--dur);
}
.nav-link:hover {
  background: rgba(255,255,255,0.1);
  color: #fff;
}

.auth-toggle {
  display: flex;
  align-items: center;
  justify-content: center;
  min-width: var(--control-height);
  min-height: var(--control-height);
  padding: 0;
  border: 1px solid rgba(255,255,255,0.18);
  border-radius: var(--radius-sm);
  background: transparent;
  color: rgba(255,255,255,0.92);
  cursor: pointer;
  font-family: inherit;
  transition: background-color var(--dur), color var(--dur), border-color var(--dur);
}
.auth-toggle:hover {
  background: rgba(255,255,255,0.1);
  color: #fff;
}
.auth-toggle svg {
  width: 22px;
  height: 22px;
  flex-shrink: 0;
  display: block;
}
.auth-toggle.logged-in { color: var(--accent); }
.auth-toggle.logged-in svg circle:nth-of-type(2) {
  fill: currentColor;
  stroke: none;
}

/* ── Sheet (inline panel under header) — not a modal ─────────
 * Use for auth, filters, compact forms. No backdrop; page scrolls.
 * For blocking overlays use .modal below.
 */
.auth-panel {
  background: rgba(255,255,255,0.02);
  border-bottom: 1px solid var(--border-subtle);
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease-out;
}
.auth-panel.open { max-height: 300px; }
.auth-panel-inner {
  padding: var(--space-6);
  max-width: 400px;
  margin: 0 auto;
}
.auth-tabs {
  display: flex;
  gap: var(--space-2);
  margin-bottom: var(--space-4);
}
.auth-tab {
  flex: 1;
  min-height: var(--control-height-sm);
  padding: 0 var(--space-4);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  font-family: inherit;
  font-size: var(--text-sm);
  font-weight: 600;
  transition: background-color var(--dur), color var(--dur), border-color var(--dur);
}
.auth-tab.active {
  background: var(--surface-2);
  color: var(--text-primary);
  border-color: var(--border-strong);
}
.auth-form input {
  width: 100%;
  padding: var(--space-3) var(--space-4);
  margin-bottom: var(--space-3);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--surface-1);
  color: var(--text-primary);
  font-size: var(--text-sm);
  font-family: inherit;
}
.auth-submit {
  width: 100%;
  min-height: var(--control-height);
  padding: 0 var(--space-4);
  border: none;
  border-radius: var(--radius-sm);
  background: var(--accent);
  color: #fff;
  font-family: inherit;
  font-weight: 600;
  font-size: var(--text-sm);
  cursor: pointer;
  transition: background-color var(--dur);
}
.auth-submit:hover { background: var(--accent-bright); }
#authUser {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}
.auth-username {
  color: var(--text-primary);
  font-weight: 600;
}
.auth-logout {
  min-height: var(--control-height-sm);
  padding: 0 var(--space-3);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-muted);
  cursor: pointer;
  font-family: inherit;
  font-size: var(--text-sm);
  font-weight: 600;
  transition: background-color var(--dur), color var(--dur), border-color var(--dur);
}
.auth-logout:hover {
  background: var(--surface-2);
  color: var(--text-primary);
}
.auth-divider {
  height: 1px;
  background: var(--border-subtle);
}

/* ── Modal (blocking overlay) ──────────────────────────────── */
.modal[hidden] {
  display: none !important;
}
.modal {
  position: fixed;
  inset: 0;
  z-index: var(--z-modal);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-4);
}
.modal__backdrop {
  position: absolute;
  inset: 0;
  background: rgba(2, 4, 12, 0.72);
  backdrop-filter: blur(4px);
}
.modal__dialog {
  position: relative;
  z-index: 1;
  display: flex;
  flex-direction: column;
  width: min(100%, 440px);
  max-height: min(88vh, 560px);
  overflow: hidden;
  background: var(--surface-1);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-modal);
}
.modal__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  padding: var(--space-4) var(--space-6);
  border-bottom: 1px solid var(--border-subtle);
}
.modal__header h2 {
  font-size: var(--text-lg);
  font-weight: 600;
  color: var(--text-primary);
}
.modal__body {
  padding: var(--space-6);
  overflow: auto;
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.55;
}
.modal__body code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  font-size: 0.9em;
  color: var(--text-primary);
}
.modal__footer {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: var(--space-2);
  padding: var(--space-4) var(--space-6);
  border-top: 1px solid var(--border-subtle);
}

/* ── Card ──────────────────────────────────────────────────── */
/*
 * GOTCHA: backdrop-filter creates a stacking context — dropdowns inside
 * a card can be clipped by a later card's stacking context. Fix by adding
 * position: relative; z-index: 10 to the card that owns the open dropdown.
 *
 * Default: static surface (no hover lift — avoids generic “dashboard demo”).
 * Use .card--interactive for raised hover + entrance motion.
 *
 * GOTCHA: a <button> or <a> used AS a card does not inherit body text color —
 * buttons default to canvas text (near-black), rendering invisible on the dark
 * bg. When a card is an interactive element, set color: var(--text-primary)
 * and font-family: var(--font) explicitly on it.
 */
.card {
  background: var(--surface-1);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  padding: var(--space-6);
  margin-bottom: var(--space-6);
  backdrop-filter: blur(10px);
  transition: border-color var(--dur), box-shadow var(--dur);
}
.card:hover {
  border-color: var(--border-strong);
  box-shadow: 0 8px 20px rgba(15, 23, 42, 0.45);
}
.card--interactive {
  transition:
    transform var(--dur) ease-out,
    box-shadow var(--dur) ease-out,
    border-color var(--dur);
  animation: fadeIn 0.35s ease-out both;
}
.card--interactive:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-card);
  border-color: var(--border-strong);
}
.card--enter {
  animation: fadeIn 0.35s ease-out both;
}
.card--flat:hover {
  box-shadow: none;
}

/* ── Button press feedback ─────────────────────────────────── */
button:active,
.btn:active,
.nav-link:active,
.auth-toggle:active,
.auth-tab:active,
.auth-submit:active,
.auth-logout:active {
  transform: scale(0.98);
  transition-duration: var(--dur-fast);
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(6px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Skeleton loading ──────────────────────────────────────── */
@keyframes shimmer { to { background-position: -200% 0; } }
.skeleton {
  background: linear-gradient(90deg, var(--surface-1) 25%, var(--surface-2) 50%, var(--surface-1) 75%);
  background-size: 200% 100%;
  animation: shimmer 1.5s ease-in-out infinite;
  border-radius: var(--radius);
}

/* ── Toast ─────────────────────────────────────────────────── */
.toast {
  position: fixed;
  bottom: var(--space-6);
  right: var(--space-6);
  z-index: var(--z-toast);
  max-width: min(360px, calc(100vw - var(--space-8)));
  background: var(--surface-toast);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: var(--space-3) var(--space-4);
  font-size: var(--text-sm);
  color: var(--text-primary);
  box-shadow: var(--shadow-card);
  pointer-events: none;
  transform: translateY(8px);
  opacity: 0;
  transition: opacity 0.2s ease-out, transform 0.2s ease-out;
}
.toast.visible {
  opacity: 1;
  transform: translateY(0);
}

/* ── Footer ────────────────────────────────────────────────── */
.info-footer {
  text-align: center;
  padding: var(--space-6) var(--space-6) 28px;
  color: var(--text-muted);
  font-size: .78em;
  line-height: 1.8;
  border-top: 1px solid var(--border-subtle);
  margin-top: var(--space-8);
}
.footer-link {
  color: var(--text-muted);
  text-decoration: none;
  transition: color var(--dur);
}
.footer-link:hover,
.footer-link:focus-visible {
  color: var(--text-secondary);
  text-decoration: underline;
}

/* ── Focus styles ──────────────────────────────────────────── */
:focus-visible {
  outline: 2px solid var(--accent-bright);
  outline-offset: 2px;
}

/* ── Skip link ─────────────────────────────────────────────── */
.skip-link {
  position: absolute;
  top: -100%;
  left: var(--space-4);
  z-index: 1000;
  padding: var(--space-2) var(--space-4);
  background: var(--accent-bright);
  color: #000;
  font-weight: 600;
  font-size: var(--text-sm);
  border-radius: 0 0 var(--radius-sm) var(--radius-sm);
  text-decoration: none;
  transition: top var(--dur);
}
.skip-link:focus { top: 0; }

/* ── Reduced motion ────────────────────────────────────────── */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
  .card--interactive:hover { transform: none; }
}

/* ── Responsive ────────────────────────────────────────────── */
@media (max-width: 600px) {
  .header-bar { padding: 0 var(--space-4); }
  .container { padding: var(--space-4); }
  .toast {
    left: var(--space-4);
    right: var(--space-4);
    max-width: none;
  }
}

/* ══════════════════════════════════════════════════════════════
   Primer — learning hub + track pages
   ══════════════════════════════════════════════════════════════ */

:root { --primer-accent: #6366f1; }
.container { max-width: 960px; }

/* Shared: accent-tinted tag chips */
.tag {
  display: inline-flex;
  align-items: center;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-secondary);
  background: rgba(255,255,255,.05);
  border: 1px solid var(--border);
}
.chip {
  display: inline-flex;
  align-items: center;
  padding: 5px 12px;
  border-radius: 999px;
  font-size: var(--text-xs);
  font-weight: 600;
  color: var(--text-secondary);
  background: rgba(99,102,241,.1);
  border: 1px solid rgba(99,102,241,.25);
}

/* Progress bar */
.progress {
  height: 8px;
  border-radius: 999px;
  background: rgba(255,255,255,.07);
  overflow: hidden;
}
.progress--thin { height: 5px; margin-top: var(--space-3); }
.progress__bar {
  height: 100%;
  border-radius: 999px;
  background: var(--track-accent, var(--primer-accent));
  transition: width var(--dur) ease-out;
}

/* ── Hero ──────────────────────────────────────────────────── */
.hero {
  padding: var(--space-8) 0 var(--space-6);
  border-bottom: 1px solid var(--border-subtle);
  margin-bottom: var(--space-8);
}
.hero__eyebrow {
  font-size: var(--text-sm);
  font-weight: 700;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--primer-accent);
  margin-bottom: var(--space-3);
}
.hero__title {
  font-size: clamp(1.6rem, 4vw, 2.4rem);
  font-weight: 700;
  line-height: 1.15;
  letter-spacing: -.01em;
  max-width: 22ch;
  margin-bottom: var(--space-4);
}
.hero__lead {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  line-height: 1.6;
  max-width: 62ch;
}
.hero__meta {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-top: var(--space-6);
}
.hero__progress {
  display: flex;
  align-items: center;
  gap: var(--space-4);
  margin-top: var(--space-6);
  max-width: 420px;
}
.hero__progress .progress { flex: 1; }
.hero__progress-label {
  font-size: var(--text-sm);
  color: var(--text-muted);
  white-space: nowrap;
}

/* ── Level sections ────────────────────────────────────────── */
.level { margin-bottom: var(--space-8); }
.level__head {
  display: flex;
  align-items: baseline;
  gap: var(--space-4);
  margin-bottom: var(--space-4);
}
.level__badge {
  flex-shrink: 0;
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--primer-accent);
  padding: 4px 10px;
  border-radius: var(--radius-sm);
  background: rgba(99,102,241,.1);
  border: 1px solid rgba(99,102,241,.25);
}
.level__name {
  font-size: var(--text-xl);
  font-weight: 600;
}
.level__blurb {
  font-size: var(--text-sm);
  color: var(--text-muted);
  margin-top: 2px;
}

/* ── Track cards (hub) ─────────────────────────────────────── */
.track-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: var(--space-4);
}
.track-card {
  display: flex;
  flex-direction: column;
  gap: var(--space-3);
  text-decoration: none;
  color: inherit;
  margin-bottom: 0;
  position: relative;
  overflow: hidden;
}
.track-card::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 3px;
  background: var(--track-accent, var(--primer-accent));
  opacity: .8;
}
.track-card:hover { border-color: color-mix(in oklch, var(--track-accent) 45%, var(--border)); }
.track-card__top {
  display: flex;
  align-items: center;
  gap: var(--space-2);
}
.track-card__dot {
  width: 10px; height: 10px;
  border-radius: 50%;
  background: var(--track-accent, var(--primer-accent));
  box-shadow: 0 0 10px var(--track-accent, var(--primer-accent));
  flex-shrink: 0;
}
.track-card__title {
  font-size: var(--text-lg);
  font-weight: 700;
}
.track-card__check {
  margin-left: auto;
  color: var(--track-accent, var(--primer-accent));
  font-weight: 700;
}
.track-card__tagline {
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--text-secondary);
}
.track-card__objective {
  font-size: var(--text-sm);
  color: var(--text-muted);
  line-height: 1.5;
  flex: 1;
}
.track-card__stack {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
}
.track-card__foot {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: var(--text-xs);
  color: var(--text-muted);
  margin-top: 2px;
}
.track-card__prog {
  font-weight: 700;
  color: var(--track-accent, var(--primer-accent));
}

/* ── Track page ────────────────────────────────────────────── */
.track-page { --track-accent: var(--primer-accent); padding-bottom: var(--space-8); }
.back-link {
  display: inline-block;
  font-size: var(--text-sm);
  font-weight: 600;
  color: var(--text-muted);
  text-decoration: none;
  margin: var(--space-4) 0 var(--space-6);
  transition: color var(--dur);
}
.back-link:hover { color: var(--text-primary); }

.track-head { margin-bottom: var(--space-6); }
.track-head__level {
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--track-accent);
}
.track-head__title {
  font-size: clamp(1.8rem, 5vw, 2.6rem);
  font-weight: 700;
  letter-spacing: -.01em;
  margin: var(--space-2) 0;
  background: linear-gradient(90deg, var(--text-primary), var(--track-accent));
  -webkit-background-clip: text;
  background-clip: text;
  -webkit-text-fill-color: transparent;
}
.track-head__tagline {
  font-size: var(--text-lg);
  color: var(--text-secondary);
}

.objective {
  margin-bottom: var(--space-6);
  border-left: 3px solid var(--track-accent);
}
.objective__label {
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: .06em;
  text-transform: uppercase;
  color: var(--track-accent);
  margin-bottom: var(--space-2);
}
.objective__text {
  font-size: var(--text-base);
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-4);
}
.objective__stack {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
}
.objective__stack-label {
  font-size: var(--text-sm);
  color: var(--text-muted);
  font-weight: 600;
}

.track-intro {
  font-size: var(--text-lg);
  color: var(--text-secondary);
  line-height: 1.7;
  margin-bottom: var(--space-6);
}

/* Setup card */
.setup { margin-bottom: var(--space-6); }
.setup__title {
  font-size: var(--text-lg);
  font-weight: 700;
  margin-bottom: var(--space-2);
}
.setup__body {
  font-size: var(--text-base);
  color: var(--text-secondary);
  line-height: 1.6;
  margin-bottom: var(--space-4);
}

/* ── Steps (pet project walkthrough) ───────────────────────── */
.steps {
  list-style: none;
  counter-reset: step;
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
}
.step {
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  background: var(--surface-1);
  padding: var(--space-6);
  transition: border-color var(--dur);
}
.step--done {
  border-color: color-mix(in oklch, var(--track-accent) 35%, var(--border));
  background: color-mix(in oklch, var(--track-accent) 5%, var(--surface-1));
}
.step__head {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  margin-bottom: var(--space-4);
}
.step__num {
  flex-shrink: 0;
  width: 30px; height: 30px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 50%;
  font-size: var(--text-sm);
  font-weight: 700;
  color: #fff;
  background: var(--track-accent);
}
.step__title {
  font-size: var(--text-lg);
  font-weight: 700;
  flex: 1;
  min-width: 0;
}
.step__toggle {
  flex-shrink: 0;
  min-height: var(--control-height-sm);
  padding: 0 var(--space-3);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-muted);
  font-family: inherit;
  font-size: var(--text-xs);
  font-weight: 700;
  cursor: pointer;
  transition: all var(--dur);
}
.step__toggle:hover { background: var(--surface-2); color: var(--text-primary); }
.step__toggle[aria-pressed="true"] {
  color: var(--track-accent);
  border-color: color-mix(in oklch, var(--track-accent) 45%, var(--border));
  background: color-mix(in oklch, var(--track-accent) 12%, transparent);
}
.step__body { color: var(--text-secondary); }
.step__body p { line-height: 1.7; margin-bottom: var(--space-4); font-size: var(--text-base); }
.step__body p:last-child { margin-bottom: 0; }
.prose-list {
  margin: 0 0 var(--space-4) var(--space-4);
  padding-left: var(--space-3);
  display: flex;
  flex-direction: column;
  gap: var(--space-2);
}
.prose-list li { line-height: 1.6; }
.step__body code,
.setup__body code,
.note-block code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  font-size: 0.88em;
  padding: 1px 6px;
  border-radius: 4px;
  background: rgba(255,255,255,.07);
  color: var(--text-primary);
}

/* ── Code blocks ───────────────────────────────────────────── */
.code-block {
  margin: var(--space-4) 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background: #0a0e1c;
}
.code-block__bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-2) var(--space-3);
  background: rgba(255,255,255,.03);
  border-bottom: 1px solid var(--border-subtle);
}
.code-block__lang {
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: var(--text-muted);
}
.code-block__copy {
  min-height: 28px;
  padding: 0 var(--space-3);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: transparent;
  color: var(--text-secondary);
  font-family: inherit;
  font-size: var(--text-xs);
  font-weight: 700;
  cursor: pointer;
  transition: all var(--dur);
}
.code-block__copy:hover { background: var(--surface-2); color: var(--text-primary); }
.code-block__copy--done {
  color: #4ade80;
  border-color: rgba(74,222,128,.4);
}
.code-block pre {
  margin: 0;
  padding: var(--space-4);
  overflow-x: auto;
}
.code-block code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  font-size: 0.86rem;
  line-height: 1.6;
  color: #e2e8f0;
  white-space: pre;
}

/* ── Output blocks ─────────────────────────────────────────── */
.output-block {
  margin: var(--space-4) 0;
  border: 1px dashed var(--border);
  border-radius: var(--radius);
  background: rgba(74,222,128,.04);
  padding: var(--space-3) var(--space-4) var(--space-4);
}
.output-block__label {
  display: inline-block;
  font-size: var(--text-xs);
  font-weight: 700;
  letter-spacing: .04em;
  text-transform: uppercase;
  color: #4ade80;
  margin-bottom: var(--space-2);
}
.output-block pre { margin: 0; overflow-x: auto; }
.output-block code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas, "Liberation Mono", monospace;
  font-size: 0.82rem;
  line-height: 1.5;
  color: var(--text-secondary);
  white-space: pre;
}

/* ── Note blocks ───────────────────────────────────────────── */
.note-block {
  display: flex;
  gap: var(--space-3);
  margin: var(--space-4) 0;
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius);
  background: rgba(99,102,241,.07);
  border: 1px solid rgba(99,102,241,.2);
}
.note-block__icon {
  flex-shrink: 0;
  width: 20px; height: 20px;
  display: flex; align-items: center; justify-content: center;
  border-radius: 50%;
  font-size: 12px;
  font-weight: 700;
  font-style: italic;
  color: #fff;
  background: var(--primer-accent);
}
.note-block p {
  font-size: var(--text-sm);
  color: var(--text-secondary);
  line-height: 1.55;
  margin: 0 !important;
}

/* ── Track footer nav ──────────────────────────────────────── */
.track-footer {
  margin-top: var(--space-8);
  padding-top: var(--space-6);
  border-top: 1px solid var(--border-subtle);
  display: flex;
  justify-content: flex-end;
}

@media (max-width: 600px) {
  .step { padding: var(--space-4); }
  .track-footer { justify-content: stretch; }
  .track-footer .btn { width: 100%; }
}
