/* ============================================================
   base.css — Connecting the Dots
   Shared styles: variables, reset, nav, typography, utilities.
   All pages load this. Page-specific styles go in their own CSS.
   ============================================================ */

/* ── CSS Variables ── */
:root {
  --bg:        #FDFBF7;
  --text:      #4A3F35;
  --accent:    #D48C70;
  --surface:   #F4EFE6;
  --border:    #E8DFD1;
  --muted:     #847769;
  --dark:      #2D241E;
  --highlight: rgba(212, 140, 112, 0.15);
  --card-bg:   #FFFFFF;
  --code-bg:   var(--surface);
  --code-text: #5A4E42;
  
  /* Glass Switcher specific */
  --c-glass: #bbbbbc;
  --glass-reflex-light: 1;
  --glass-reflex-dark: 1;
  --saturation: 150%;
}
:root {
  --math-box-bg: #FBF6F2;
  --math-box-border: #D99A74;
  --math-box-label-bg: #D18B61;
  --math-box-label-text: #1E1A17;

  --proof-box-label-bg: #EEDDD3;
  --proof-box-label-text: #7B5D50;

  --note-box-bg: #FFF9F5;

  --table-rule: #EAD8CF;
}

[data-theme="dark"] {
  --bg:        #16100C;
  --text:      #C5B49A;
  --accent:    #D48C70;
  --surface:   #1F1510;
  --border:    #2E2018;
  --muted:     #736050;
  --dark:      #EAD9C2;
  --highlight: rgba(212, 140, 112, 0.12);
  --card-bg:   #1C1208;
  --code-bg:   #130E0A;
  --code-text: #B0A088;
  
  /* Glass Switcher specific */
  --glass-reflex-light: 0.3;
  --glass-reflex-dark: 2;
}
[data-theme="dark"] {
  --math-box-bg: #221712;
  --math-box-border: #7A5037;
  --math-box-label-bg: #A56747;
  --math-box-label-text: #F7E8D8;

  --proof-box-label-bg: #34231B;
  --proof-box-label-text: #D2AE97;

  --note-box-bg: #261A14;

  --table-rule: #3A281F;
}
/* ── Reset ── */
* { margin: 0; padding: 0; box-sizing: border-box; }

/* Lenis smooth-scroll shims (no-op if Lenis not loaded) */
html.lenis, html.lenis body { height: auto; }
.lenis.lenis-smooth { scroll-behavior: auto !important; }
.lenis.lenis-smooth [data-lenis-prevent] { overscroll-behavior: contain; }
.lenis.lenis-stopped { overflow: clip; }
.lenis.lenis-smooth iframe { pointer-events: none; }

html { scroll-behavior: smooth; }

/* ── Body ── */
body {
  font-family: 'Lora', Georgia, serif;
  background: var(--bg);
  color: var(--text);
  font-size: 1.15rem;
  line-height: 1.8;
  overflow-x: hidden;
  opacity: 0;
  /* Only fade-in on page load; color changes are instant via html[data-theme] */
  transition: opacity 0.5s ease;
}
body.loaded { opacity: 1; }

/* ── Smooth theme transitions ── */
.theme-transitioning body,
.theme-transitioning nav,
.theme-transitioning .anatomy-card,
.theme-transitioning .chapter-sample,
.theme-transitioning .ch-topics-block,
.theme-transitioning .cta-section,
.theme-transitioning .philosophy-block,
.theme-transitioning .code-block,
.theme-transitioning .progress-bar-wrap,
.theme-transitioning .glass-hamburger,
.theme-transitioning .mob-theme-toggle,
.theme-transitioning .btn,
.theme-transitioning .pill-tag,
.theme-transitioning mark,
.theme-transitioning .tax-items span,
.theme-transitioning .ch-topics-header,
.theme-transitioning .collab-list .tag,
.theme-transitioning footer,
.theme-transitioning .rule {
  transition:
    background-color 350ms cubic-bezier(0.4, 0, 0.2, 1),
    border-color     350ms cubic-bezier(0.4, 0, 0.2, 1),
    color            350ms cubic-bezier(0.4, 0, 0.2, 1),
    box-shadow       350ms cubic-bezier(0.4, 0, 0.2, 1) !important;
}

.theme-transitioning h1, .theme-transitioning h2, .theme-transitioning h3,
.theme-transitioning p, .theme-transitioning a, .theme-transitioning li,
.theme-transitioning blockquote, .theme-transitioning .lede p,
.theme-transitioning .tax-root, .theme-transitioning .tax-branch-label,
.theme-transitioning .ch-label, .theme-transitioning .pct,
.theme-transitioning .eq-math, .theme-transitioning .eq-comment,
.theme-transitioning .card-title, .theme-transitioning .card-num,
.theme-transitioning .anatomy-card p {
  transition: color 350ms cubic-bezier(0.4, 0, 0.2, 1) !important;
}

.page-wrap { max-width: 900px; margin: 0 auto; padding: 0 3rem; }

/* ── Reading Progress Bar ── */
.reading-progress {
  position: fixed; top: 0; left: 0; height: 4px;
  width: 0%; background: var(--accent); z-index: 2000;
  transition: width 0.1s linear;
}

/* ────────────────────────────────────────────────────────────
   NAVIGATION (Editorial Layout)
   ──────────────────────────────────────────────────────────── */
nav {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 1rem;
  font-family: -apple-system, BlinkMacSystemFont, sans-serif;
  font-size: 0.95rem;
  font-weight: 500;
  letter-spacing: 0.01em;
  padding: 0.75rem 4rem;
  border-bottom: none; /* REMOVED BORDER HERE */
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: color-mix(in srgb, var(--bg) 85%, transparent);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

nav.nav-sticky {
  position: sticky;
  top: 0;
  z-index: 1000;
}

nav.nav-static {
  position: relative;
}

nav a { color: var(--muted); text-decoration: none; transition: color 0.2s; }
nav a:hover, nav a.active { color: var(--accent); }

.nav-center {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 2.5rem;
}

.nav-center a { position: relative; padding-bottom: 2px; }
.nav-center a::after {
  content: ""; position: absolute; left: 0; bottom: -4px;
  width: 0; height: 1px; background: var(--accent);
  transition: width 0.3s cubic-bezier(0.22, 1, 0.36, 1);
}
.nav-center a:hover::after, .nav-center a.active::after { width: 100%; }

.nav-right {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  gap: 1.5rem;
}

.exp-nav {
  display: inline-flex; align-items: center; gap: 6px; line-height: 1;
  text-decoration: none; color: var(--text); opacity: 0.9; transition: all 0.2s ease;
}
.exp-nav:hover { opacity: 1; transform: translateY(-1px); }
.exp-icon { width: 24px; height: 24px; }
.github-icon { width: 24px; height: 24px; opacity: 0.85; transition: all 0.2s ease; }
.github-link:hover .github-icon { opacity: 1; transform: translateY(-1px); }

/* ── THEME TOGGLE (Sun/Moon Morph) ── */
.theme-toggle {
  background: none;
  border: none;
  cursor: pointer;
  width: 38px;
  height: 38px;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  color: var(--muted);
  border-radius: 50%;
  transition: color 0.2s ease, background-color 0.2s ease;
}

.theme-toggle:hover {
  color: var(--accent);
  background: color-mix(in srgb, var(--surface) 80%, transparent);
}
.theme-toggle:focus { outline: none; }

.theme-toggle svg {
  position: absolute; width: 19px; height: 19px;
  transition: transform 0.5s cubic-bezier(0.34, 1.56, 0.64, 1), opacity 0.3s ease;
  pointer-events: none;
}

/* Morph State */
.moon-icon { opacity: 0; transform: scale(0.4) rotate(-45deg); }
.sun-icon  { opacity: 1; transform: scale(1) rotate(0); }

[data-theme="dark"] .sun-icon  { opacity: 0; transform: scale(0.4) rotate(45deg); }
[data-theme="dark"] .moon-icon { opacity: 1; transform: scale(1) rotate(0); color: var(--text); }


/* ────────────────────────────────────────────────────────────
   MOBILE NAVIGATION (Header Row & Top Drawer)
   ──────────────────────────────────────────────────────────── */
.mobile-top-controls { display: none; }
.top-drawer { display: none; }

@media (max-width: 680px) {
  /* Break Desktop Grid */
  nav {
    display: flex; flex-direction: column; align-items: stretch;
    padding: 0; gap: 0; border-bottom: none;
    margin-left: -1rem; margin-right: -1rem;
    width: calc(100% + 2rem);
    /* Keep sticky so no blank reserved space appears below the bar */
    position: sticky; top: 0;
    background-color: color-mix(in srgb, var(--bg) 92%, transparent);
    backdrop-filter: blur(12px); -webkit-backdrop-filter: blur(12px);
  }

  .nav-desktop-only, nav .exp-nav, .nav-right { display: none !important; }

  /* Mobile Top Bar */
  .mobile-top-controls {
    display: grid; grid-template-columns: 1fr auto 1fr; align-items: center;
    width: 100%; padding: 10px 2rem; border-bottom: none; /* REMOVED BORDER HERE */
  }

  .mobile-top-controls .top-ham {
    justify-self: start; display: flex; flex-direction: column; gap: 5px;
    width: 32px; height: 42px; align-items: flex-start; justify-content: center;
    cursor: pointer; padding: 4px 0;
  }
  .mobile-top-controls .top-ham:active { opacity: 0.6; }
  .mobile-top-controls .top-ham span {
    display: block; width: 22px; height: 2px; background: var(--muted);
    border-radius: 2px; transition: transform 0.25s ease, opacity 0.2s ease;
  }
  .mobile-top-controls .top-ham.is-open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
  .mobile-top-controls .top-ham.is-open span:nth-child(2) { opacity: 0; transform: scaleX(0); }
  .mobile-top-controls .top-ham.is-open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

  .mobile-top-controls .top-logo  { justify-self: center; }
  .mobile-top-controls .theme-toggle { justify-self: end; margin-right: -8px; }

  /* Top Drawer - FIXED GAP ISSUE */
  .top-drawer {
    display: grid; grid-template-rows: 0fr; overflow: hidden;
    transition: grid-template-rows 0.38s cubic-bezier(0.22, 1, 0.36, 1), opacity 0.28s ease;
    opacity: 0;
  }
  .top-drawer.is-open { 
    grid-template-rows: 1fr; opacity: 1; border-bottom: none; /* REMOVED BORDER HERE */
  }

  /* min-height: 0 is required for 0fr grid squishing to work perfectly */
  .top-drawer-links { 
    list-style: none; padding: 0 1.5rem; margin: 0; text-align: left; min-height: 0; 
  }
  .top-drawer-links a {
    display: block; padding: 12px 0; font-family: -apple-system, sans-serif;
    font-size: 0.95rem; font-weight: 600; color: var(--muted); text-decoration: none;
    border-bottom: 1px solid var(--border); transition: color 0.15s;
  }
  .top-drawer-links li:last-child a { border-bottom: none; }
  .top-drawer-links a:hover { color: var(--accent); }
}

/* ────────────────────────────────────────────────────────────
   MOBILE FLOATING BUTTONS
   ──────────────────────────────────────────────────────────── */
.floating-controls, .floating-theme-pill { display: none; }

@media (max-width: 680px) {
  .floating-controls, .floating-theme-pill {
    display: block; position: fixed; z-index: 2001;
    opacity: 0; pointer-events: none; filter: blur(20px);
    transform: translateY(28px) scale(0.8);
    transition: opacity 0.4s ease-out, transform 0.6s cubic-bezier(0.34, 1.4, 0.64, 1), filter 0.4s ease-out;
  }
  .floating-controls  { bottom: 24px; left: 20px; }
  .floating-theme-pill { bottom: 24px; right: 20px; }

  .floating-controls.floating-visible, .floating-theme-pill.floating-visible {
    opacity: 1; pointer-events: auto; transform: translateY(0) scale(1); filter: blur(0px);
  }
  .floating-hidden {
    opacity: 0 !important; pointer-events: none !important;
    transform: translateY(28px) scale(0.8) !important; filter: blur(20px);
    transition: opacity 0.3s ease-in, transform 0.3s ease, filter 0.3s ease-in !important;
  }
}

/* ── Floating Theme Button — matches .glass-hamburger premium glass ── */
/* High specificity (.mob-theme-toggle.theme-toggle) to override the top nav's transparent background */
.mob-theme-toggle.theme-toggle {
  position: relative;
  width: 54px; height: 54px; border-radius: 27px;
  border: 1px solid color-mix(in srgb, var(--border) 70%, transparent);
  cursor: pointer; overflow: hidden;
  background: color-mix(in srgb, var(--surface) 92%, transparent);
  backdrop-filter: blur(24px) saturate(160%); -webkit-backdrop-filter: blur(24px) saturate(160%);
  display: flex; align-items: center; justify-content: center;
  box-shadow:
    inset 0 0 0 1px color-mix(in srgb, #fff calc(var(--glass-reflex-light) * 10%), transparent),
    inset 1px 2px 0px -1px color-mix(in srgb, #fff calc(var(--glass-reflex-light) * 90%), transparent),
    inset -1px -1px 0px -1px color-mix(in srgb, #fff calc(var(--glass-reflex-light) * 80%), transparent),
    inset 0px -1px 2px 0px color-mix(in srgb, #000 calc(var(--glass-reflex-dark) * 12%), transparent),
    0px 1px 3px 0px color-mix(in srgb, #000 calc(var(--glass-reflex-dark) * 10%), transparent),
    0px 4px 16px 0px color-mix(in srgb, #000 calc(var(--glass-reflex-dark) * 12%), transparent);
  transition:
    transform 0.38s cubic-bezier(0.34, 1.1, 0.64, 1),
    box-shadow 0.25s ease;
}

.mob-theme-toggle.theme-toggle:hover {
  background: color-mix(in srgb, var(--surface) 92%, transparent);
  color: var(--accent);
}

.mob-theme-toggle.theme-toggle:active { transform: scale(0.93); }

.mob-theme-toggle.theme-toggle svg {
  position: absolute; width: 22px; height: 22px; color: var(--muted); pointer-events: none;
  transition: transform 0.5s cubic-bezier(0.34, 1.56, 0.64, 1), opacity 0.3s ease, color 0.2s ease;
}

html[data-theme="light"] .mob-theme-toggle.theme-toggle .moon-icon { opacity: 0; transform: scale(0.4) rotate(-45deg); }
html[data-theme="light"] .mob-theme-toggle.theme-toggle .sun-icon  { opacity: 1; transform: scale(1) rotate(0); }

html[data-theme="dark"] .mob-theme-toggle.theme-toggle .sun-icon  { opacity: 0; transform: scale(0.4) rotate(45deg); }
html[data-theme="dark"] .mob-theme-toggle.theme-toggle .moon-icon { opacity: 1; transform: scale(1) rotate(0); color: var(--accent); }

/* ── Floating Hamburger Navigation Card ── */
.glass-hamburger {
  position: relative; width: 54px; height: 54px; border-radius: 27px;
  border: 1px solid color-mix(in srgb, var(--border) 70%, transparent);
  cursor: pointer; overflow: hidden;
  background: color-mix(in srgb, var(--surface) 92%, transparent);
  backdrop-filter: blur(24px) saturate(160%); -webkit-backdrop-filter: blur(24px) saturate(160%);
  box-shadow:
    inset 0 0 0 1px color-mix(in srgb, #fff calc(var(--glass-reflex-light) * 10%), transparent),
    inset 1px 2px 0px -1px color-mix(in srgb, #fff calc(var(--glass-reflex-light) * 90%), transparent),
    inset -1px -1px 0px -1px color-mix(in srgb, #fff calc(var(--glass-reflex-light) * 80%), transparent),
    inset 0px -1px 2px 0px color-mix(in srgb, #000 calc(var(--glass-reflex-dark) * 12%), transparent),
    0px 1px 3px 0px color-mix(in srgb, #000 calc(var(--glass-reflex-dark) * 10%), transparent),
    0px 4px 16px 0px color-mix(in srgb, #000 calc(var(--glass-reflex-dark) * 12%), transparent);
  transition:
    width       0.38s cubic-bezier(0.34, 1.1, 0.64, 1),
    height      0.38s cubic-bezier(0.34, 1.1, 0.64, 1),
    border-radius 0.38s cubic-bezier(0.34, 1.1, 0.64, 1),
    box-shadow  0.25s ease;
}
.glass-hamburger:active:not(.is-active) { transform: scale(0.93); }
.glass-hamburger.is-active {
  width: 160px; height: 230px; border-radius: 20px; cursor: default;
  box-shadow:
    inset 0 0 0 1px color-mix(in srgb, #fff calc(var(--glass-reflex-light) * 10%), transparent),
    inset 1px 2px 0px -1px color-mix(in srgb, #fff calc(var(--glass-reflex-light) * 90%), transparent),
    inset -1px -1px 0px -1px color-mix(in srgb, #fff calc(var(--glass-reflex-light) * 80%), transparent),
    inset 0px -1px 2px 0px color-mix(in srgb, #000 calc(var(--glass-reflex-dark) * 12%), transparent),
    0px 8px 32px 0px color-mix(in srgb, #000 calc(var(--glass-reflex-dark) * 18%), transparent),
    0px 2px 8px 0px color-mix(in srgb, #000 calc(var(--glass-reflex-dark) * 10%), transparent);
}

.hamburger-icon {
  position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%);
  display: flex; flex-direction: column; gap: 5px; width: 20px;
  pointer-events: none; opacity: 1; transition: opacity 0.15s ease;
}
.glass-hamburger.is-active .hamburger-icon { opacity: 0; }
.hamburger-icon span { display: block; height: 2px; width: 20px; background: var(--dark); border-radius: 2px; }

.hamburger-close-hit { position: absolute; inset: 0; cursor: pointer; z-index: 10; display: none; }
.glass-hamburger.is-active .hamburger-close-hit { display: block; }

.glass-nav-content {
  position: absolute; inset: 0; padding: 12px 8px; opacity: 0;
  pointer-events: none; transition: opacity 0.15s ease; display: flex; flex-direction: column; z-index: 11;
}
.glass-hamburger.is-active .glass-nav-content { opacity: 1; pointer-events: auto; transition: opacity 0.22s 0.22s ease; }

.glass-nav-label {
  font-family: -apple-system, BlinkMacSystemFont, sans-serif; font-size: 0.6rem; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase; color: var(--accent); margin-bottom: 8px; padding-left: 10px;
}

.glass-nav-links { list-style: none; padding: 0; margin: 0; display: flex; flex-direction: column; gap: 1px; }
.glass-nav-links a {
  display: flex; align-items: center; gap: 10px; padding: 8px 10px; border-radius: 10px;
  font-family: -apple-system, sans-serif; font-size: 0.83rem; font-weight: 600; color: var(--text);
  text-decoration: none; white-space: nowrap; transition: background 0.12s, color 0.12s;
}
.glass-nav-links a:hover, .glass-nav-links a:active { background: var(--highlight); color: var(--accent); }
.glass-nav-links .nav-icon { width: 13px; height: 13px; flex-shrink: 0; opacity: 0.55; }


/* ────────────────────────────────────────────────────────────
   TYPOGRAPHY & GLOBAL LAYOUT
   ──────────────────────────────────────────────────────────── */
h1 { font-size: clamp(3rem, 7vw, 4.5rem); font-weight: 400; line-height: 1.05; margin: 0 0 1rem; color: var(--dark); letter-spacing: -0.02em; }
h1 em { font-style: italic; color: var(--accent); }
h2 { font-size: 1.8rem; font-weight: 600; margin: 3.5rem 0 1rem; color: var(--dark); }
h3 { font-family: -apple-system, sans-serif; font-size: 0.85rem; font-weight: 600; letter-spacing: 0.15em; text-transform: uppercase; color: var(--accent); margin: 2.5rem 0 1rem; }
h3 a { text-decoration: none; color: inherit; }

.subtitle { font-size: 1.25rem; color: var(--muted); font-style: italic; margin-top: 1.5rem; }
p { margin-bottom: 1.5rem; }
mark { background: var(--highlight); color: var(--dark); padding: 0.1em 0.3em; border-radius: 4px; }
.prose { animation: fadeUp 0.9s 0.15s ease both; }
blockquote { font-style: italic; border-left: 3px solid var(--accent); padding-left: 1.5rem; color: var(--muted); margin: 2rem 0; font-size: 1.1rem; }

.rule { display: flex; align-items: center; gap: 1rem; color: var(--muted); margin: 3rem 0; }
.rule::before, .rule::after { content: ''; flex: 1; height: 1px; background: var(--border); }
.rule span { font-family: -apple-system, sans-serif; font-size: 0.75rem; font-weight: 600; letter-spacing: 0.15em; text-transform: uppercase; }

.label-caps { font-family: -apple-system, sans-serif; font-size: 0.7rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.12em; color: var(--accent); }
.pill-tag { font-family: -apple-system, sans-serif; font-size: 0.7rem; font-weight: 500; color: var(--muted); background: var(--bg); border: 1px solid var(--border); padding: 0.3em 0.8em; border-radius: 20px; display: inline-block; }

.btn { display: inline-flex; align-items: center; justify-content: center; background: var(--surface); color: var(--dark); text-decoration: none; padding: 0.7rem 1.4rem; border-radius: 30px; font-family: -apple-system, sans-serif; font-size: 0.82rem; font-weight: 600; border: 1px solid var(--border); transition: all 0.2s; cursor: pointer; }
.btn:hover { background: var(--bg); border-color: var(--accent); color: var(--accent); transform: translateY(-2px); box-shadow: 0 4px 12px var(--highlight); }
.btn.primary { background: var(--accent); color: var(--bg); border: none; padding: 1rem 2.2rem; font-size: 0.95rem; border-radius: 999px; box-shadow: 0 10px 25px rgba(212, 140, 112, 0.25), 0 4px 10px rgba(0,0,0,0.06); transition: all 0.25s ease; }
.btn.primary:hover { transform: translateY(-2px) scale(1.03); box-shadow: 0 18px 40px rgba(212, 140, 112, 0.35), 0 6px 14px rgba(0,0,0,0.08); background: #cf7f61; }
.btn.primary::after { content: ""; position: absolute; inset: -2px; border-radius: inherit; background: radial-gradient(circle, rgba(212,140,112,0.25), transparent 70%); opacity: 0; transition: opacity 0.3s ease; z-index: -1; }
.btn.primary:active { transform: translateY(1px) scale(0.98); box-shadow: 0 6px 12px rgba(0,0,0,0.1); }
.btn.primary:hover::after { opacity: 1; }

/* ────────────────────────────────────────────────────────────
   INDEX PAGE COMPONENTS
   ──────────────────────────────────────────────────────────── */
.main-header { display: flex; align-items: center; justify-content: space-between; gap: 2rem; padding: 2rem 0 1rem; animation: fadeUp 0.9s ease both; }
.header-content { flex: 1; padding-bottom: 0px; }
.chapter-label { font-size: 0.85rem; font-weight: 600; letter-spacing: 0.15em; margin-bottom: 1.5rem; display: block; }
.header-cta { margin-top: 2rem; animation: fadeUp 0.9s 0.2s ease both; }
.widget-container { display: flex; justify-content: center; width: 100%; }
.book-widget-frame { width: 280px; height: 340px; border: none; overflow: hidden; display: block; }

.lede { margin: 3rem auto 2rem; border-left: 3px solid var(--accent); padding-left: 1.5rem; animation: fadeUp 0.9s 0.15s ease both; }
.lede p { font-size: 1.25rem; color: var(--dark); }

.philosophy-block { background: var(--surface); padding: 2rem 2.5rem; border-radius: 16px; border: 1px solid var(--border); animation: fadeUp 0.9s 0.25s ease both; }

.anatomy-card, .chapter-sample, .ch-topics-block, .cta-section { background: var(--card-bg); border: 1px solid var(--border); border-radius: 12px; transition: all 0.35s ease; }

.book-anatomy { margin: 2.5rem 0; display: grid; grid-template-columns: 1fr 1fr; gap: 1.5rem; animation: fadeUp 0.9s 0.3s ease both; }
.anatomy-card { padding: 1.5rem; box-shadow: 0 4px 12px rgba(0,0,0,0.03); }
.anatomy-card:hover { transform: translateY(-3px); border-color: var(--accent); box-shadow: 0 8px 20px var(--highlight); }
.anatomy-card .card-num { font-family: -apple-system, sans-serif; font-size: 0.75rem; font-weight: 600; color: var(--accent); margin-bottom: 0.5rem; }
.anatomy-card .card-title { font-size: 1.2rem; font-weight: 600; color: var(--dark); margin-bottom: 0.5rem; }
.anatomy-card p { font-size: 0.95rem; color: var(--muted); line-height: 1.6; margin: 0; }

.chapter-sample { padding: 2.5rem; margin: 3rem 0; animation: fadeUp 0.9s 0.4s ease both; border-radius: 16px; }
.sample-label { font-size: 0.8rem; font-weight: 600; letter-spacing: 0.15em; margin-bottom: 1.5rem; border-bottom: 2px solid var(--surface); padding-bottom: 0.5rem; }

.tax-root { font-size: 1.4rem; font-weight: 600; color: var(--dark); margin-bottom: 1rem; }
.tax-branch-label { font-size: 1.2rem; font-weight: 600; color: var(--dark); margin: 2.5rem 0 0.2rem; padding-bottom: 0.3rem; border-bottom: 1px solid var(--border); }
.tax-desc { font-size: 0.9rem; color: var(--muted); font-style: italic; margin-bottom: 1rem; padding-left: 0.5rem; }
.tax-section { padding-left: 1.5rem; border-left: 2px solid var(--surface); margin: 1.5rem 0; }
.tax-section-title { font-size: 1.05rem; font-weight: 600; color: var(--text); margin-bottom: 0.5rem; }
.tax-dim { color: var(--muted); font-weight: 400; font-size: 0.9rem; font-style: italic; }
.tax-group { padding-left: 1.2rem; border-left: 1px dashed var(--border); margin-top: 0.8rem; margin-bottom: 1.2rem; }
.tax-group-title { font-size: 0.8rem; margin-bottom: 0.6rem; }
.tax-items { display: flex; flex-wrap: wrap; gap: 0.5rem; }
.tax-items span:hover { border-color: var(--accent); color: var(--accent); }

.code-block { font-family: ui-monospace, monospace; font-size: 0.95rem; background: var(--code-bg); padding: 1.5rem 2rem; border-radius: 12px; margin: 1.5rem 0; color: var(--code-text); border: 1px solid var(--border); line-height: 1.8; transition: background-color 0.35s, color 0.35s; }
.eq-row { margin-bottom: 1rem; }
.eq-row:last-child { margin-bottom: 0; }
.eq-comment { color: var(--accent); font-family: 'Lora', serif; font-style: italic; font-size: 0.9rem; display: block; }
.eq-math { font-size: 1.1rem; color: var(--dark); }

.progress-block { margin: 2rem 0; }
.progress-row { display: flex; align-items: center; gap: 1rem; margin-bottom: 1rem; }
.ch-label { font-family: -apple-system, sans-serif; font-size: 0.85rem; font-weight: 600; color: var(--text); width: 140px; }
.progress-bar-wrap { flex: 1; height: 8px; background: var(--surface); border-radius: 99px; overflow: hidden; position: relative; }
.progress-bar-fill { position: absolute; left: 0; top: 0; bottom: 0; border-radius: 99px; transition: width 1.2s cubic-bezier(0.22,1,0.36,1); width: 0; }
.progress-bar-fill.draft { background: var(--accent); }
.pct { width: 2.8rem; text-align: right; font-family: -apple-system, sans-serif; font-size: 0.85rem; font-weight: 600; color: var(--muted); }
.ch-updated { font-family: -apple-system, sans-serif; font-size: 0.72rem; color: var(--muted); font-style: italic; margin-bottom: 1rem; opacity: 0.75; }

.ch-toggle { cursor: pointer; user-select: none; }
.ch-toggle .toggle-arrow { display: inline-block; font-size: 0.7rem; color: var(--accent); margin-left: 0.4rem; transition: transform 0.3s ease; }
.ch-toggle.open .toggle-arrow { transform: rotate(90deg); }
.ch-topics-collapsible { display: grid; grid-template-rows: 0fr; opacity: 0; margin-top: 0; margin-bottom: 0; transition: grid-template-rows 0.45s cubic-bezier(0.22,1,0.36,1), margin 0.45s cubic-bezier(0.22,1,0.36,1), opacity 0.35s ease; }
.ch-topics-collapsible > div { overflow: hidden; }
.ch-topics-collapsible.open { grid-template-rows: 1fr; margin-top: 0.6rem; margin-bottom: 0.6rem; opacity: 1; }

.ch-topics-block { border-radius: 16px; overflow: hidden; margin: 0; }
.ch-topics-header { background: var(--surface); padding: 0.75rem 1.2rem; border-bottom: 1px solid var(--border); font-family: -apple-system, sans-serif; font-weight: 600; font-size: 0.85rem; color: var(--dark); display: flex; align-items: center; justify-content: space-between; gap: 1rem; }
.ch-topics-header .exp-link { font-size: 0.72rem; font-weight: 600; color: var(--accent); text-decoration: none; border: 1px solid var(--accent); padding: 0.28em 0.85em; border-radius: 20px; letter-spacing: 0.04em; white-space: nowrap; transition: background 0.2s, color 0.2s; flex-shrink: 0; }
.ch-topics-header .exp-link:hover { background: var(--accent); color: #fff; }
.ch-topics-grid { display: grid; grid-template-columns: 1fr 1fr; }
.ch-topic-group { padding: 1rem 1.2rem; }
.ch-topic-group:first-child { border-right: 1px solid var(--border); }
.ch-topic-section { font-size: 0.75rem; font-weight: 700; letter-spacing: 0.1em; margin-bottom: 0.6rem; }
.ch-topic { font-size: 0.88rem; color: var(--text); display: flex; align-items: flex-start; gap: 0.5rem; margin-bottom: 0.3rem; line-height: 1.4; }
.ch-topic::before { content: '✓'; color: var(--accent); font-family: -apple-system, sans-serif; font-weight: bold; font-size: 0.8rem; margin-top: 0.1rem; }

.collab-list { margin: 2rem 0; list-style: none; }
.collab-list li { display: flex; align-items: flex-start; gap: 1.2rem; padding: 1.2rem 0; border-bottom: 1px solid var(--border); }
.collab-list li:last-child { border-bottom: none; }
.collab-list .tag { flex-shrink: 0; background: var(--surface); padding: 0.4em 0.8em; border-radius: 20px; margin-top: 0.2rem; }

.cta-section { margin: 4rem 0 2rem; padding: 3rem; border-radius: 16px; text-align: center; }
.cta-section h2 { margin: 0 0 1rem; }
.cta-section p { color: var(--muted); margin-bottom: 2rem; }

@media (max-width: 768px) {
  .page-wrap { padding: 0 1rem; }
  .main-header { flex-direction: column-reverse; align-items: center; text-align: center; padding-top: 1rem; padding-bottom: 1rem; }
  .widget-container { margin-top: 0; }
  .book-anatomy, .ch-topics-grid { grid-template-columns: 1fr; }
  .ch-topic-group:first-child { border-right: none; border-bottom: 1px solid var(--border); }
}

@media (max-width: 680px) {
  h1 { font-size: 2.5rem; margin-bottom: 0.4rem; }
  .subtitle { font-size: 0.95rem; line-height: 1.55; margin-top: 0.5rem; opacity: 0.9; }
  .chapter-label { font-size: 0.65rem; letter-spacing: 0.14em; opacity: 0.9; margin-bottom: 0.6rem; color: color-mix(in srgb, var(--accent) 85%, var(--muted)); }
  .main-header { padding-top: 0.5rem; }
}

.chapter-label { white-space: normal; }
@media (min-width: 768px) { .chapter-label { white-space: nowrap; } }

/* ── Footer ── */
footer { padding: 3rem 0 4rem; text-align: center; font-family: -apple-system, BlinkMacSystemFont, sans-serif; font-size: 0.85rem; color: var(--muted); border-top: 1px solid var(--border); margin-top: 4rem; }

/* ── Animations ── */
@keyframes fadeUp { from { opacity: 0; transform: translateY(18px); } to { opacity: 1; transform: translateY(0); } }
.iframe-shield { position: absolute; inset: 0; z-index: 2; pointer-events: none; }