:root {
  --bg: #060606;
  --panel: rgba(255, 255, 255, 0.035);
  --panel-strong: rgba(255, 255, 255, 0.06);
  --border: rgba(255, 255, 255, 0.14);
  --border-strong: rgba(255, 255, 255, 0.3);
  --fg: #f5f7fb;
  --muted: rgba(245, 247, 251, 0.76);
  --dim: rgba(245, 247, 251, 0.5);
  --glow: rgba(255, 255, 255, 0.08);
  --concept: #d7e2ff;
  --strategy: #ffc27a;
  --execution: #8ed8ff;
  --review: #d5b8ff;
  --done: #a8ffb8;
  --font-ui: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", Inter, "Helvetica Neue", Arial, sans-serif;
  --font-mono: "JetBrainsMono Nerd Font", "Hack Nerd Font", "SFMono-Regular", "CaskaydiaMono Nerd Font", ui-monospace, Menlo, Consolas, monospace;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  background:
    radial-gradient(circle at top center, rgba(255,255,255,0.08), transparent 42%),
    #050505;
  color: var(--fg);
  font-family: var(--font-ui);
  line-height: 1.65;
}

body::after {
  content: "";
  position: fixed;
  inset: 0;
  background: repeating-linear-gradient(
    0deg,
    transparent,
    transparent 2px,
    rgba(0, 0, 0, 0.08) 2px,
    rgba(0, 0, 0, 0.08) 4px
  );
  pointer-events: none;
  z-index: 20;
}

a {
  color: inherit;
}

button,
select,
textarea {
  font: inherit;
}

code,
pre,
textarea,
.mono,
.badge,
.stat strong,
.lesson-position,
.back,
.smallcaps {
  font-family: var(--font-mono);
}

.site-shell {
  width: min(1080px, calc(100vw - 28px));
  margin: 0 auto;
  padding: 22px 0 80px;
  position: relative;
  z-index: 1;
}

.back {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  color: var(--dim);
  text-decoration: none;
  font-size: 13px;
  margin-bottom: 16px;
}

.back:hover {
  color: var(--fg);
}

.hero,
.panel,
.lesson-card,
.module-panel,
.note-panel,
.stats-panel,
.lesson-nav,
.callout,
.code-block,
.footer-panel {
  border: 1px solid var(--border);
  background: linear-gradient(180deg, rgba(255,255,255,0.04), rgba(255,255,255,0.02));
  box-shadow: 0 0 0 1px rgba(255,255,255,0.02) inset;
}

.hero,
.panel,
.lesson-card,
.module-panel,
.note-panel,
.stats-panel,
.lesson-nav,
.callout,
.code-block,
.footer-panel {
  padding: 18px;
}

.hero {
  overflow: hidden;
  position: relative;
}

.hero-content,
.lesson-header {
  position: relative;
  z-index: 1;
}

.eyebrow,
.smallcaps {
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--dim);
  text-transform: uppercase;
}

.hero h1,
.lesson-title {
  font-size: clamp(2.2rem, 5vw, 4rem);
  line-height: 1.05;
  letter-spacing: -0.03em;
  margin: 10px 0 14px;
}

.hero p,
.lesson-hook,
.muted {
  color: var(--muted);
}

.hero-grid,
.stats-grid,
.lesson-layout {
  display: grid;
  gap: 16px;
}

.hero-grid {
  grid-template-columns: 1.25fr 0.75fr;
}

.stats-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.stat {
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.025);
  padding: 14px;
}

.stat strong {
  display: block;
  font-size: 1.4rem;
  margin-bottom: 5px;
}

.stat span {
  color: var(--dim);
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.12em;
}

.note-list,
.reveal-list,
.lesson-bullets {
  list-style: none;
  padding: 0;
  margin: 0;
}

.note-list li,
.reveal-list li,
.lesson-bullets li {
  position: relative;
  padding-left: 18px;
  color: var(--muted);
  margin-bottom: 10px;
}

.note-list li::before,
.reveal-list li::before,
.lesson-bullets li::before {
  content: ">";
  position: absolute;
  left: 0;
  color: var(--dim);
}

.module-section {
  margin-top: 22px;
}

.module-heading {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: baseline;
  border-bottom: 1px dashed var(--border);
  padding-bottom: 8px;
  margin-bottom: 14px;
}

.module-heading h2 {
  margin: 0;
  font-size: 1.2rem;
}

.module-heading span {
  color: var(--dim);
  font-size: 0.9rem;
}

.lesson-link-grid {
  display: grid;
  gap: 10px;
}

.lesson-link {
  display: grid;
  gap: 8px;
  text-decoration: none;
  padding: 14px;
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.025);
  transition: 0.18s ease;
}

.lesson-link:hover,
.button:hover {
  background: rgba(255,255,255,0.075);
  border-color: var(--border-strong);
  box-shadow: 0 0 14px var(--glow);
}

.lesson-link-top,
.lesson-header-top,
.lesson-controls,
.lesson-nav-row,
.module-top {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  justify-content: space-between;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  border: 1px solid var(--border);
  padding: 5px 8px;
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--muted);
  background: rgba(255,255,255,0.03);
}

.badge.type-concept { color: var(--concept); }
.badge.type-strategy { color: var(--strategy); }
.badge.type-execution { color: var(--execution); }
.badge.type-review { color: var(--review); }
.badge.type-done { color: var(--done); }

.button {
  border: 1px solid var(--border);
  background: rgba(255,255,255,0.03);
  color: var(--fg);
  cursor: pointer;
  padding: 10px 12px;
  text-decoration: none;
}

.button.secondary {
  color: var(--muted);
}

pre {
  margin: 0;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
  color: #f7f7f7;
}

.code-block {
  overflow: auto;
}

.lesson-layout {
  grid-template-columns: minmax(0, 1fr) 300px;
}

.lesson-main,
.lesson-sidebar {
  display: grid;
  gap: 16px;
}

.lesson-position {
  color: var(--dim);
  font-size: 0.85rem;
}

.lesson-nav a {
  text-decoration: none;
}

.lesson-nav-row > * {
  flex: 1;
}

.footer-panel {
  margin-top: 28px;
}

@media (max-width: 980px) {
  .hero-grid,
  .lesson-layout,
  .stats-grid {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 640px) {
  .site-shell {
    width: min(100vw - 18px, 100%);
    padding-top: 12px;
  }

  .hero,
  .panel,
  .lesson-card,
  .module-panel,
  .note-panel,
  .stats-panel,
  .lesson-nav,
  .callout,
  .code-block,
  .footer-panel {
    padding: 14px;
  }

  .hero h1,
  .lesson-title {
    font-size: clamp(1.8rem, 8vw, 2.6rem);
  }
}