/* AI PM Course — v2 redesign */

:root {
  --bg:         #0d1117;
  --surface:    #161b22;
  --surface-2:  #21262d;
  --border:     #30363d;
  --border-2:   #444c56;
  --text:       #e6edf3;
  --muted:      #8b949e;
  --muted-2:    #6e7681;
  --accent:     #4493f8;
  --accent-dim: rgba(68, 147, 248, 0.12);
  --green:      #3fb950;
  --yellow:     #d29922;

  --font:  "DM Sans", system-ui, -apple-system, sans-serif;
  --mono:  "JetBrains Mono", "SF Mono", Consolas, monospace;

  --nav-h:  56px;
  --sub-h:  44px;
  --r:      8px;
  --r-sm:   5px;
  --max:    820px;
  --shadow: 0 8px 32px rgba(0,0,0,0.5);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { -webkit-font-smoothing: antialiased; scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.65;
  min-height: 100vh;
  padding-top: var(--nav-h); /* offset for fixed topnav */
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

/* ── Top navigation ─────────────────────────────────── */

.topnav {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  width: 100%;
  height: var(--nav-h);
  background: rgba(13, 17, 23, 0.96);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
  display: flex;
  flex-direction: row;
  flex-wrap: nowrap;
  align-items: center;
  padding: 0 1.25rem;
  gap: 1rem;
  -webkit-transform: translateZ(0); /* Safari fixed-pos fix */
  transform: translateZ(0);
}

.topnav-logo {
  font-size: 0.92rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  color: var(--text);
  white-space: nowrap;
  flex-shrink: 0;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.topnav-logo:hover { color: var(--accent); text-decoration: none; }
.topnav-logo-dot {
  width: 7px; height: 7px;
  background: var(--accent);
  border-radius: 50%;
  display: inline-block;
  flex-shrink: 0;
}

.topnav-nav {
  display: flex;
  align-items: center;
  gap: 0.15rem;
  flex: 1;
}

.topnav-nav a,
.topnav-nav button {
  padding: 0.38rem 0.7rem;
  border-radius: var(--r-sm);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--muted);
  border: none;
  background: none;
  cursor: pointer;
  font-family: inherit;
  white-space: nowrap;
  display: flex;
  align-items: center;
  gap: 0.3rem;
  transition: color 0.1s, background 0.1s;
}
.topnav-nav a:hover,
.topnav-nav button:hover {
  color: var(--text);
  background: var(--surface-2);
  text-decoration: none;
}
.topnav-nav a.active { color: var(--accent); background: var(--accent-dim); }

/* dropdown */
.nav-dropdown {
  position: relative;
}
.nav-dropdown-panel {
  display: none;
  position: absolute;
  top: calc(100% + 6px);
  left: 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 0.5rem;
  min-width: 180px;
  box-shadow: var(--shadow);
  z-index: 300;
}
.nav-dropdown-panel.weeks-panel {
  min-width: 220px;
}
.nav-dropdown.open .nav-dropdown-panel { display: block; }

.nav-dropdown-panel a {
  display: block;
  padding: 0.42rem 0.65rem;
  border-radius: var(--r-sm);
  font-size: 0.82rem;
  color: var(--muted);
  white-space: nowrap;
}
.nav-dropdown-panel a:hover { color: var(--text); background: var(--surface-2); text-decoration: none; }
.nav-dropdown-panel a.active { color: var(--accent); }

.week-nav-grid {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 3px;
}
.week-nav-grid a {
  text-align: center;
  padding: 0.35rem 0;
  font-size: 0.78rem;
  font-weight: 600;
  font-family: var(--mono);
  border-radius: 4px;
  background: var(--surface-2);
  color: var(--muted);
  border: 1px solid var(--border);
}
.week-nav-grid a:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }
.week-nav-grid a.active { border-color: var(--accent); color: var(--accent); background: var(--accent-dim); }

.nav-dropdown-label {
  font-size: 0.63rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--muted-2);
  padding: 0.35rem 0.65rem 0.2rem;
}

.topnav-right {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

/* hamburger */
.topnav-hamburger {
  display: none;
  padding: 0.4rem 0.55rem;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: var(--r-sm);
  color: var(--text);
  cursor: pointer;
  font-size: 1rem;
  line-height: 1;
  margin-left: auto;
}

/* ── Context subnav ──────────────────────────────────── */

.subnav {
  position: sticky;
  top: 0; /* body already offset by nav-h, so sticky top:0 sits right under topnav */
  z-index: 100;
  background: rgba(13, 17, 23, 0.96);
  border-bottom: 1px solid var(--border);
  height: var(--sub-h);
  display: flex;
  align-items: center;
  padding: 0 1.5rem;
  gap: 0.75rem;
  overflow-x: auto;
  scrollbar-width: none;
}
.subnav::-webkit-scrollbar { display: none; }

.subnav-sep { width: 1px; height: 16px; background: var(--border); flex-shrink: 0; }

.subnav a {
  font-size: 0.8rem;
  color: var(--muted);
  white-space: nowrap;
  padding: 0.22rem 0.5rem;
  border-radius: var(--r-sm);
  flex-shrink: 0;
  font-weight: 500;
}
.subnav a:hover { color: var(--text); background: var(--surface-2); text-decoration: none; }
.subnav a.active { color: var(--accent); font-weight: 600; }

.subnav-label {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--muted-2);
  white-space: nowrap;
  flex-shrink: 0;
}

/* week progress pills in subnav */
.week-pills {
  display: flex;
  gap: 2px;
  align-items: center;
}
.week-pill {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 26px;
  height: 22px;
  border-radius: 4px;
  font-size: 0.68rem;
  font-weight: 700;
  font-family: var(--mono);
  color: var(--muted-2);
  background: var(--surface);
  border: 1px solid var(--border);
  flex-shrink: 0;
  padding: 0;
}
.week-pill:hover { border-color: var(--wc, var(--accent)); color: var(--wc, var(--accent)); text-decoration: none; }
.week-pill.active {
  background: var(--wc, var(--accent));
  border-color: var(--wc, var(--accent));
  color: #fff;
}

/* ── Page container ──────────────────────────────────── */

.page {
  max-width: var(--max);
  margin: 0 auto;
  padding: 2.5rem 1.5rem 5rem;  /* body already has nav-h padding-top */
}
.page.has-subnav {
  padding-top: calc(var(--sub-h) + 2rem); /* body offset + subnav height */
}
.page.wide {
  max-width: 1060px;
}
.page.narrow {
  max-width: 680px;
}

/* ── Hero (home) ─────────────────────────────────────── */

.hero {
  text-align: center;
  padding: 3.5rem 0 2rem;
}
.hero h1 {
  font-size: clamp(1.85rem, 4.5vw, 2.8rem);
  font-weight: 800;
  letter-spacing: -0.04em;
  line-height: 1.12;
  margin-bottom: 1rem;
  background: linear-gradient(135deg, var(--text) 40%, var(--accent) 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.hero p {
  font-size: 1.05rem;
  color: var(--muted);
  max-width: 48ch;
  margin: 0 auto 1.75rem;
  line-height: 1.6;
}
.hero-ctas {
  display: flex;
  gap: 0.75rem;
  justify-content: center;
  flex-wrap: wrap;
}
.time-pill {
  display: inline-flex;
  align-items: center;
  font-size: 0.78rem;
  font-weight: 500;
  color: var(--muted);
  border: 1px solid var(--border);
  padding: 0.22rem 0.75rem;
  border-radius: 999px;
  margin-bottom: 1.25rem;
}

/* ── Buttons ─────────────────────────────────────────── */

.btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  padding: 0.6rem 1.2rem;
  border-radius: var(--r);
  font-size: 0.88rem;
  font-weight: 600;
  font-family: inherit;
  cursor: pointer;
  border: 1px solid transparent;
  text-decoration: none;
  transition: transform 0.1s, opacity 0.1s;
  white-space: nowrap;
}
.btn:hover { transform: translateY(-1px); text-decoration: none; }
.btn-primary { background: var(--accent); color: #fff; }
.btn-primary:hover { opacity: 0.88; }
.btn-outline { background: transparent; border-color: var(--border); color: var(--text); }
.btn-outline:hover { border-color: var(--accent); color: var(--accent); }

/* ── Course roadmap ──────────────────────────────────── */

.section-label {
  font-size: 0.68rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.09em;
  color: var(--muted-2);
  margin-bottom: 1rem;
}

.phase-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(210px, 1fr));
  gap: 0.65rem;
  margin-bottom: 2.5rem;
}
.phase-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 1rem 1.1rem;
  text-decoration: none;
  color: var(--text);
  display: block;
  transition: border-color 0.15s, transform 0.12s;
}
.phase-card:hover {
  border-color: var(--pc, var(--accent));
  transform: translateY(-2px);
  text-decoration: none;
  color: var(--text);
}
.phase-eyebrow {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--pc, var(--accent));
  margin-bottom: 0.3rem;
}
.phase-card h3 {
  font-size: 0.92rem;
  font-weight: 700;
  margin-bottom: 0.35rem;
  line-height: 1.3;
}
.phase-card p {
  font-size: 0.78rem;
  color: var(--muted);
  line-height: 1.45;
  margin-bottom: 0.75rem;
}
.phase-week-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 0.3rem;
}
.phase-week-chip {
  font-size: 0.7rem;
  font-weight: 700;
  font-family: var(--mono);
  padding: 0.18rem 0.55rem;
  border-radius: 4px;
  background: var(--surface-2);
  color: var(--muted);
  border: 1px solid var(--border);
  text-decoration: none;
}
.phase-week-chip:hover {
  background: var(--accent-dim);
  border-color: var(--accent);
  color: var(--accent);
  text-decoration: none;
}

/* ── How-to / steps row ──────────────────────────────── */

.start-box {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 1.5rem 1.75rem;
  margin-bottom: 2rem;
}
.start-box h2 {
  font-size: 1rem;
  font-weight: 700;
  margin-bottom: 1.25rem;
}
.steps-row {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(195px, 1fr));
  gap: 1.25rem;
}
.step-item {
  display: flex;
  gap: 0.75rem;
  align-items: flex-start;
}
.step-n {
  width: 1.7rem;
  height: 1.7rem;
  border-radius: 50%;
  background: var(--accent-dim);
  border: 1px solid var(--accent);
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 700;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  margin-top: 0.05rem;
}
.step-item strong { display: block; font-size: 0.875rem; margin-bottom: 0.25rem; }
.step-item p { margin: 0; font-size: 0.8rem; color: var(--muted); line-height: 1.5; }

/* ── Quick links ─────────────────────────────────────── */

.quick-links {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 0.65rem;
}
.qlink {
  display: flex;
  align-items: flex-start;
  gap: 0.75rem;
  padding: 0.9rem 1rem;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r);
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.12s, transform 0.1s;
}
.qlink:hover { border-color: var(--accent); transform: translateY(-1px); text-decoration: none; color: var(--text); }
.qlink-icon { font-size: 1.15rem; flex-shrink: 0; margin-top: 0.05rem; }
.qlink strong { display: block; font-size: 0.875rem; font-weight: 600; margin-bottom: 0.2rem; }
.qlink span { font-size: 0.78rem; color: var(--muted); line-height: 1.4; }

/* ── Week page ───────────────────────────────────────── */

.week-header {
  margin-bottom: 1.5rem;
}
.week-meta {
  display: flex;
  align-items: center;
  gap: 0.65rem;
  margin-bottom: 0.75rem;
  flex-wrap: wrap;
}
.phase-badge {
  display: inline-flex;
  align-items: center;
  height: 1.5rem;
  padding: 0 0.65rem;
  border-radius: 4px;
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  white-space: nowrap;
  background: color-mix(in srgb, var(--pb) 18%, transparent);
  color: var(--pb);
  border: 1px solid color-mix(in srgb, var(--pb) 40%, transparent);
}
.week-num {
  font-size: 0.75rem;
  color: var(--muted);
  font-weight: 600;
}
.week-title {
  font-size: 1.55rem;
  font-weight: 800;
  letter-spacing: -0.03em;
  line-height: 1.2;
  margin-bottom: 0.4rem;
}
.week-focus {
  font-size: 0.92rem;
  color: var(--muted);
  line-height: 1.5;
}

.learn-link-strip {
  display: flex;
  align-items: center;
  gap: 0.6rem;
  padding: 0.65rem 1rem;
  background: var(--accent-dim);
  border: 1px solid rgba(68, 147, 248, 0.3);
  border-radius: var(--r);
  font-size: 0.85rem;
  margin-bottom: 1.5rem;
  flex-wrap: wrap;
}
.learn-link-strip .pill {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--accent);
  background: rgba(68,147,248,0.15);
  padding: 0.15rem 0.5rem;
  border-radius: 3px;
}

/* ── Week tabs ───────────────────────────────────────── */

.week-tabs {
  display: flex;
  gap: 0;
  border-bottom: 2px solid var(--border);
  margin-bottom: 0;
  overflow-x: auto;
  scrollbar-width: none;
}
.week-tabs::-webkit-scrollbar { display: none; }
.week-tabs button {
  padding: 0.65rem 1.1rem;
  border: none;
  background: none;
  color: var(--muted);
  font-size: 0.875rem;
  font-weight: 500;
  cursor: pointer;
  font-family: inherit;
  white-space: nowrap;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  transition: color 0.12s;
  line-height: 1;
}
.week-tabs button:hover { color: var(--text); }
.week-tabs button.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
  font-weight: 600;
}

/* ── Tab panels ──────────────────────────────────────── */

[hidden] { display: none !important; }

.tab-panel {
  padding-top: 1.75rem;
  animation: fadeUp 0.12s ease;
}
@keyframes fadeUp {
  from { opacity: 0; transform: translateY(5px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ── Pager ───────────────────────────────────────────── */

.week-pager {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 3rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--border);
}
.pager-link {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-size: 0.875rem;
  font-weight: 600;
  padding: 0.55rem 1rem;
  border-radius: var(--r);
  border: 1px solid var(--border);
  background: var(--surface);
  color: var(--muted);
  text-decoration: none;
  transition: border-color 0.12s, color 0.12s;
}
.pager-link:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }

/* ── Work tip ────────────────────────────────────────── */

.work-tip {
  margin-top: 1.5rem;
  padding: 0.85rem 1.1rem;
  background: var(--surface);
  border: 1px dashed var(--border);
  border-radius: var(--r);
  font-size: 0.82rem;
  color: var(--muted);
  line-height: 1.55;
}
.work-tip strong { color: var(--text); }

/* ── Prose / content ─────────────────────────────────── */

.prose {
  font-size: 0.95rem;
  line-height: 1.75;
  color: var(--text);
}
.prose h1 {
  font-size: 1.45rem;
  font-weight: 700;
  letter-spacing: -0.025em;
  margin: 0 0 1rem;
  padding-bottom: 0.65rem;
  border-bottom: 1px solid var(--border);
}
.prose h2 {
  font-size: 1.05rem;
  font-weight: 700;
  margin: 2rem 0 0.6rem;
  color: var(--text);
}
.prose h3 {
  font-size: 0.95rem;
  font-weight: 600;
  margin: 1.5rem 0 0.5rem;
  color: var(--text);
}
.prose p { margin: 0.65rem 0; }
.prose ul, .prose ol { margin: 0.65rem 0; padding-left: 1.5rem; }
.prose li { margin: 0.3rem 0; }

.prose table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.875rem;
  margin: 1.25rem 0;
  border-radius: var(--r);
  overflow: hidden;
  border: 1px solid var(--border);
}
.prose th {
  background: var(--surface);
  font-weight: 600;
  font-size: 0.8rem;
  text-align: left;
  padding: 0.55rem 0.75rem;
  border-bottom: 1px solid var(--border);
  color: var(--muted);
}
.prose td {
  padding: 0.5rem 0.75rem;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}
.prose tr:last-child td { border-bottom: none; }
.prose tr:hover td { background: var(--surface); }

.prose pre {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 1rem 1.1rem;
  overflow-x: auto;
  font-family: var(--mono);
  font-size: 0.82rem;
  line-height: 1.55;
  margin: 1rem 0;
}
.prose code {
  font-family: var(--mono);
  font-size: 0.875em;
  background: var(--surface-2);
  padding: 0.1rem 0.38rem;
  border-radius: 4px;
  border: 1px solid var(--border);
  color: var(--text);
}
.prose pre code {
  padding: 0; background: none; border: none; font-size: 1em;
}
.prose blockquote {
  margin: 1rem 0;
  padding: 0.65rem 1rem;
  border-left: 3px solid var(--accent);
  color: var(--muted);
  background: var(--accent-dim);
  border-radius: 0 var(--r) var(--r) 0;
  font-style: italic;
}
.prose strong { color: var(--text); font-weight: 600; }
.prose hr { border: none; border-top: 1px solid var(--border); margin: 1.75rem 0; }

/* also apply prose styles to md-body */
.md-body { font-size: 0.95rem; line-height: 1.75; }
.md-body h1 { font-size:1.45rem;font-weight:700;letter-spacing:-0.025em;margin:0 0 1rem;padding-bottom:0.65rem;border-bottom:1px solid var(--border); }
.md-body h2 { font-size:1.05rem;font-weight:700;margin:2rem 0 0.6rem; }
.md-body h3 { font-size:0.95rem;font-weight:600;margin:1.5rem 0 0.5rem; }
.md-body p { margin:0.65rem 0; }
.md-body ul,.md-body ol { margin:0.65rem 0;padding-left:1.5rem; }
.md-body li { margin:0.3rem 0; }
.md-body table { width:100%;border-collapse:collapse;font-size:0.875rem;margin:1.25rem 0;border:1px solid var(--border);border-radius:var(--r);overflow:hidden; }
.md-body th { background:var(--surface);font-weight:600;font-size:0.8rem;text-align:left;padding:0.55rem 0.75rem;border-bottom:1px solid var(--border);color:var(--muted); }
.md-body td { padding:0.5rem 0.75rem;border-bottom:1px solid var(--border);vertical-align:top; }
.md-body tr:last-child td { border-bottom:none; }
.md-body tr:hover td { background:var(--surface); }
.md-body pre { background:var(--surface);border:1px solid var(--border);border-radius:var(--r);padding:1rem 1.1rem;overflow-x:auto;font-family:var(--mono);font-size:0.82rem;line-height:1.55;margin:1rem 0; }
.md-body code { font-family:var(--mono);font-size:0.875em;background:var(--surface-2);padding:0.1rem 0.38rem;border-radius:4px;border:1px solid var(--border); }
.md-body pre code { padding:0;background:none;border:none;font-size:1em; }
.md-body blockquote { margin:1rem 0;padding:0.65rem 1rem;border-left:3px solid var(--accent);color:var(--muted);background:var(--accent-dim);border-radius:0 var(--r) var(--r) 0; }
.md-body strong { color:var(--text);font-weight:600; }
.md-body hr { border:none;border-top:1px solid var(--border);margin:1.75rem 0; }

/* ── Learn hub chapter cards ─────────────────────────── */

.chapter-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(230px, 1fr));
  gap: 0.65rem;
  margin: 1rem 0 2rem;
}
.chapter-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--r);
  padding: 1.05rem 1.15rem;
  display: block;
  color: var(--text);
  text-decoration: none;
  transition: border-color 0.12s, transform 0.1s;
}
.chapter-card:hover { border-color: var(--card-accent, var(--accent)); transform: translateY(-2px); text-decoration: none; color: var(--text); }
.chapter-n { font-size: 0.65rem; color: var(--card-accent, var(--accent)); font-weight: 700; margin-bottom: 0.3rem; letter-spacing: 0.03em; }
.chapter-card strong { display: block; font-size: 0.92rem; font-weight: 700; margin-bottom: 0.25rem; }
.chapter-card p { margin: 0; font-size: 0.78rem; color: var(--muted); line-height: 1.45; }

/* ── Learn hub week mapping ──────────────────────────── */

.week-map-row {
  display: flex;
  align-items: center;
  padding: 0.55rem 0;
  border-bottom: 1px solid var(--border);
  gap: 1rem;
  font-size: 0.875rem;
}
.week-map-row:last-child { border-bottom: none; }
.week-map-chapter { flex: 1; font-weight: 600; }
.week-map-links { display: flex; gap: 0.4rem; flex-wrap: wrap; }
.week-map-links a {
  font-size: 0.75rem;
  font-family: var(--mono);
  font-weight: 700;
  padding: 0.18rem 0.55rem;
  background: var(--surface-2);
  border: 1px solid var(--border);
  border-radius: 4px;
  color: var(--muted);
  text-decoration: none;
}
.week-map-links a:hover { border-color: var(--accent); color: var(--accent); }

/* ── Mobile overlay ──────────────────────────────────── */

.mobile-overlay {
  display: none;            /* hidden by default via CSS */
  position: fixed;
  top: var(--nav-h);
  left: 0;
  right: 0;
  bottom: 0;
  width: 100%;
  background: var(--bg);
  z-index: 999;
  padding: 1.25rem 1.5rem;
  overflow-y: auto;
  -webkit-transform: translateZ(0);
  transform: translateZ(0);
}
/* shown when JS adds the .open class */
.mobile-overlay.open { display: block; }

.mob-section {
  font-size: 0.65rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--muted-2);
  padding: 1rem 0 0.4rem;
  border-top: 1px solid var(--border);
  margin-top: 0.5rem;
}
.mob-section:first-child { border-top: none; padding-top: 0; margin-top: 0; }
.mob-link {
  display: block;
  padding: 0.6rem 0;
  color: var(--muted);
  font-size: 0.9rem;
  border-bottom: 1px solid var(--border);
}
.mob-link.active { color: var(--accent); }
.mob-link:hover { color: var(--text); text-decoration: none; }
.mob-week-grid {
  display: grid;
  grid-template-columns: repeat(7, 1fr);
  gap: 4px;
  margin-top: 0.5rem;
}
.mob-week-btn {
  text-align: center;
  padding: 0.5rem 0;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 5px;
  color: var(--muted);
  font-size: 0.78rem;
  font-weight: 700;
  font-family: var(--mono);
}
.mob-week-btn:hover { border-color: var(--accent); color: var(--accent); text-decoration: none; }
.mob-week-btn.active { border-color: var(--accent); background: var(--accent-dim); color: var(--accent); }

/* ── Responsive ──────────────────────────────────────── */

@media (max-width: 700px) {
  .topnav-nav { display: none; }
  .topnav-hamburger { display: block; }
  .page { padding: 1.25rem 1rem 3rem; }
  .page.has-subnav { padding-top: calc(var(--sub-h) + 1rem); }
  .phase-grid { grid-template-columns: 1fr 1fr; }
  .steps-row { grid-template-columns: 1fr 1fr; }
  .chapter-grid { grid-template-columns: 1fr 1fr; }
  .quick-links { grid-template-columns: 1fr; }
  .hero h1 { font-size: 1.75rem; }
}
@media (max-width: 480px) {
  .phase-grid { grid-template-columns: 1fr; }
  .chapter-grid { grid-template-columns: 1fr; }
  .steps-row { grid-template-columns: 1fr; }
  .week-pills { flex-wrap: wrap; }
}

/* ── Diagram / architecture components ──────────────────── */

.diagram { margin: 1.75rem 0; overflow-x: auto; }
.diagram-label {
  font-size: 0.68rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.07em; color: var(--muted-2); margin-bottom: 0.75rem;
}
.d-flow {
  display: flex; align-items: center; flex-wrap: wrap;
  gap: 0; margin-bottom: 0.65rem;
}
.d-col { display: flex; flex-direction: column; gap: 0.5rem; }
.d-row { display: flex; align-items: center; gap: 0; flex-wrap: wrap; }
.d-node {
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: var(--r-sm); padding: 0.45rem 0.85rem;
  font-size: 0.8rem; font-weight: 500; white-space: nowrap;
  text-align: center; color: var(--text);
}
.d-node--blue  { background: rgba(68,147,248,.13); border-color: var(--accent); color: var(--accent); }
.d-node--green { background: rgba(63,185,80,.12); border-color: var(--green); color: var(--green); }
.d-node--gold  { background: rgba(210,153,34,.12); border-color: var(--yellow); color: var(--yellow); }
.d-node--red   { background: rgba(248,81,73,.12); border-color: #f85149; color: #f85149; }
.d-node--big   { padding: 0.65rem 1.1rem; font-size: 0.875rem; font-weight: 600; }
.d-arrow { color: var(--muted-2); padding: 0 0.5rem; font-size: 1rem; flex-shrink: 0; }
.d-arrow--down { text-align: center; color: var(--muted-2); font-size: 1rem; padding: 0.15rem 0; }
.d-vs { align-self: center; font-size: 0.7rem; font-weight: 700; color: var(--muted-2); padding: 0 0.65rem; }

/* ── Callout boxes ─────────────────────────────────────── */

.callout {
  padding: 1rem 1.15rem; border-radius: var(--r);
  border: 1px solid var(--border); background: var(--surface);
  margin: 1.25rem 0; font-size: 0.875rem; line-height: 1.65;
}
.callout > *:first-child { margin-top: 0; }
.callout > *:last-child  { margin-bottom: 0; }
.callout--info  { border-color: rgba(68,147,248,.4);  background: rgba(68,147,248,.07); }
.callout--warn  { border-color: rgba(210,153,34,.4);  background: rgba(210,153,34,.07); }
.callout--green { border-color: rgba(63,185,80,.4);   background: rgba(63,185,80,.07);  }
.callout--red   { border-color: rgba(248,81,73,.4);   background: rgba(248,81,73,.07);  }
.callout-title {
  font-size: 0.72rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.06em; margin-bottom: 0.4rem;
}
.callout--info  .callout-title { color: var(--accent); }
.callout--warn  .callout-title { color: var(--yellow); }
.callout--green .callout-title { color: var(--green);  }
.callout--red   .callout-title { color: #f85149;        }

/* ── Definition list ───────────────────────────────────── */

.def-list { margin: 1rem 0; }
.def-item {
  padding: 0.85rem 1rem; border: 1px solid var(--border);
  border-radius: var(--r); background: var(--surface);
  margin-bottom: 0.5rem;
}
.def-term {
  font-size: 0.9rem; font-weight: 700; color: var(--text);
  margin-bottom: 0.3rem;
}
.def-body { font-size: 0.85rem; color: var(--muted); line-height: 1.6; }
.def-body strong { color: var(--text); }

/* ── Two-column compare ─────────────────────────────────── */

.compare-grid {
  display: grid; grid-template-columns: 1fr 1fr;
  gap: 0.75rem; margin: 1.25rem 0;
}
@media (max-width: 560px) { .compare-grid { grid-template-columns: 1fr; } }
.compare-col {
  background: var(--surface); border: 1px solid var(--border);
  border-radius: var(--r); padding: 1rem 1.1rem;
}
.compare-col h4 {
  font-size: 0.82rem; font-weight: 700; margin-bottom: 0.65rem;
  padding-bottom: 0.5rem; border-bottom: 1px solid var(--border);
}
.compare-col ul { margin: 0; padding-left: 1.25rem; }
.compare-col li { font-size: 0.82rem; color: var(--muted); margin: 0.3rem 0; line-height: 1.5; }
.compare-col li strong { color: var(--text); }

/* ── Numbered concept row ──────────────────────────────── */

.concept-list { margin: 1.25rem 0; display: flex; flex-direction: column; gap: 0.6rem; }
.concept-item {
  display: flex; gap: 1rem; align-items: flex-start;
  padding: 0.9rem 1rem; background: var(--surface);
  border: 1px solid var(--border); border-radius: var(--r);
}
.concept-num {
  width: 1.8rem; height: 1.8rem; border-radius: 50%;
  background: var(--accent-dim); border: 1px solid var(--accent);
  color: var(--accent); font-size: 0.75rem; font-weight: 700;
  display: flex; align-items: center; justify-content: center; flex-shrink: 0;
}
.concept-body h4 { font-size: 0.88rem; font-weight: 700; margin-bottom: 0.25rem; }
.concept-body p  { margin: 0; font-size: 0.82rem; color: var(--muted); line-height: 1.55; }
.concept-body p strong { color: var(--text); }

/* ── PM takeaway strip ─────────────────────────────────── */

.pm-box {
  border-left: 3px solid var(--accent); background: var(--accent-dim);
  padding: 0.75rem 1rem; border-radius: 0 var(--r) var(--r) 0;
  margin: 1.25rem 0; font-size: 0.85rem; line-height: 1.6;
}
.pm-box-label {
  font-size: 0.65rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.07em; color: var(--accent); margin-bottom: 0.3rem;
}

/* ── Misc utility ───────────────────────────────────────── */

.section-eyebrow {
  font-size: 0.7rem; font-weight: 700; text-transform: uppercase;
  letter-spacing: 0.08em; color: var(--accent); margin-bottom: 0.4rem;
}

/* ── Token example visualization ────────────────────────── */

.token-vis { display: flex; flex-wrap: wrap; gap: 3px; margin: 0.75rem 0; }
.token {
  background: var(--surface-2); border: 1px solid var(--border);
  border-radius: 3px; padding: 0.2rem 0.45rem;
  font-family: var(--mono); font-size: 0.78rem;
  color: var(--text);
}
.token--t1 { border-color: #4493f8; background: rgba(68,147,248,.12); }
.token--t2 { border-color: #3fb950; background: rgba(63,185,80,.12); }
.token--t3 { border-color: #d29922; background: rgba(210,153,34,.12); }
.token--t4 { border-color: #bc8cff; background: rgba(188,140,255,.12); }