/* ============================================================
   Data Science Study Path — Glassmorphism Theme
   Shared stylesheet for home, overview, and all module pages
   ============================================================ */

/* --- CSS Variables ----------------------------------------- */
:root {
  --bg:       #0a0e17;
  --card:     rgba(22, 27, 34, 0.6);
  --card-solid: #161b22;
  --card2:    rgba(28, 33, 40, 0.5);
  --border:   rgba(48, 54, 61, 0.6);
  --text:     #e6edf3;
  --muted:    #8b949e;

  --green:    #3fb950;
  --blue:     #58a6ff;
  --orange:   #f97316;
  --purple:   #c084fc;
  --teal:     #4ec9a0;
  --red:      #ff4b4b;
  --yellow:   #cd8b00;

  /* Glass tokens */
  --glass-bg:         rgba(22, 27, 34, 0.45);
  --glass-border:     rgba(255, 255, 255, 0.06);
  --glass-blur:       16px;
  --glass-blur-heavy: 24px;
  --glass-shadow:     0 8px 32px rgba(0, 0, 0, 0.35);
  --glass-shadow-hover: 0 12px 48px rgba(0, 0, 0, 0.5);
  --glass-glow:       inset 0 1px 0 rgba(255, 255, 255, 0.05);

  /* Transitions */
  --ease: cubic-bezier(0.4, 0, 0.2, 1);
  --t-fast:   0.2s var(--ease);
  --t-smooth: 0.35s var(--ease);

  /* Fonts */
  --font: 'Segoe UI', system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'Cascadia Code', 'Fira Code', 'JetBrains Mono', Consolas, monospace;
}

/* --- Light mode overrides ---------------------------------- */
body.light-mode {
  --bg:               #f0f4f8;
  --card:             rgba(255, 255, 255, 0.75);
  --card-solid:       #ffffff;
  --card2:            rgba(240, 244, 248, 0.8);
  --border:           rgba(0, 0, 0, 0.08);
  --text:             #1a2030;
  --muted:            #5a6478;
  --glass-bg:         rgba(255, 255, 255, 0.6);
  --glass-border:     rgba(0, 0, 0, 0.07);
  --glass-shadow:     0 8px 32px rgba(0, 0, 0, 0.10);
  --glass-shadow-hover: 0 12px 48px rgba(0, 0, 0, 0.16);
  --glass-glow:       inset 0 1px 0 rgba(255, 255, 255, 0.9);
}
body.light-mode::before {
  background:
    radial-gradient(600px circle at 15% 15%, rgba(88,166,255,0.12), transparent 70%),
    radial-gradient(500px circle at 85% 25%, rgba(192,132,252,0.10), transparent 70%),
    radial-gradient(450px circle at 55% 85%, rgba(249,115,22,0.08), transparent 70%);
}
body.light-mode #star-canvas { opacity: 0.15; }
body.light-mode ::-webkit-scrollbar-thumb { background: rgba(0,0,0,0.15); }

/* Light mode: sidebar */
body.light-mode .page-module .sidebar,
body.light-mode .page-module > nav,
body.light-mode .page-module #sidebar {
  background: rgba(255,255,255,0.85);
  border-right-color: rgba(0,0,0,0.08);
}
/* Light mode: code blocks */
body.light-mode .page-module pre { filter: brightness(0.95) contrast(1.05); }

/* ── Theme toggle button ─────────────────────────────────── */
.theme-toggle {
  background: none;
  border: 1px solid var(--glass-border);
  border-radius: 8px;
  padding: 5px 10px;
  color: var(--muted);
  font-size: 1rem;
  cursor: pointer;
  transition: all 0.2s;
  line-height: 1;
  display: flex;
  align-items: center;
  gap: 5px;
}
.theme-toggle:hover {
  background: rgba(255,255,255,0.06);
  color: var(--text);
  border-color: rgba(255,255,255,0.12);
}
body.light-mode .theme-toggle:hover { background: rgba(0,0,0,0.05); }

/* --- Reset & Base ------------------------------------------ */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

/* Animated gradient orb background */
@keyframes orb-drift {
  0%   { transform: translate(0, 0) scale(1); }
  33%  { transform: translate(40px, -30px) scale(1.08); }
  66%  { transform: translate(-20px, 25px) scale(0.95); }
  100% { transform: translate(0, 0) scale(1); }
}
@keyframes orb-drift2 {
  0%   { transform: translate(0, 0) scale(1); }
  40%  { transform: translate(-35px, 20px) scale(1.06); }
  75%  { transform: translate(25px, -15px) scale(0.97); }
  100% { transform: translate(0, 0) scale(1); }
}
@keyframes orb-drift3 {
  0%   { transform: translate(0, 0) scale(1); }
  50%  { transform: translate(20px, 35px) scale(1.04); }
  100% { transform: translate(0, 0) scale(1); }
}

body::before {
  content: '';
  position: fixed;
  inset: 0;
  background:
    radial-gradient(600px circle at 15% 15%, rgba(88, 166, 255, 0.09), transparent 70%),
    radial-gradient(500px circle at 85% 25%, rgba(192, 132, 252, 0.07), transparent 70%),
    radial-gradient(450px circle at 55% 85%, rgba(249, 115, 22, 0.06), transparent 70%);
  pointer-events: none;
  z-index: 0;
  animation: orb-drift 18s ease-in-out infinite;
}

/* Noise texture overlay */
body::after {
  content: '';
  position: fixed;
  inset: 0;
  background: url("data:image/svg+xml,%3Csvg viewBox='0 0 256 256' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='.85' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='.015'/%3E%3C/svg%3E");
  pointer-events: none;
  z-index: 0;
  opacity: 0.5;
}

body > * { position: relative; z-index: 1; }

a { color: inherit; text-decoration: none; }

/* --- Scrollbar ---------------------------------------------- */
::-webkit-scrollbar { width: 8px; }
::-webkit-scrollbar-track { background: transparent; }
::-webkit-scrollbar-thumb { background: rgba(255,255,255,0.08); border-radius: 4px; }
::-webkit-scrollbar-thumb:hover { background: rgba(255,255,255,0.14); }


/* =============================================================
   MODULE PAGES (Pattern A + Pattern C)
   ============================================================= */

/* Two-column layout */
.page-module { display: flex; min-height: 100vh; font-size: 15px; }

/* --- Sidebar (Pattern A: .sidebar | Pattern C: nav | Pandas: #sidebar) --- */
.page-module .sidebar,
.page-module > nav,
.page-module #sidebar {
  width: 260px;
  min-height: 100vh;
  background: rgba(22, 27, 34, 0.7);
  backdrop-filter: blur(var(--glass-blur-heavy));
  -webkit-backdrop-filter: blur(var(--glass-blur-heavy));
  border-right: 1px solid var(--glass-border);
  box-shadow: 4px 0 24px rgba(0, 0, 0, 0.2);
  position: sticky;
  top: 0;
  height: 100vh;
  overflow-y: auto;
  flex-shrink: 0;
  z-index: 10;
}
/* Pandas sidebar: flex column layout with inner scroll */
.page-module #sidebar {
  display: flex;
  flex-direction: column;
  overflow: hidden;
  width: 280px;
}

/* Sidebar header */
.page-module .sb-head,
.page-module .sbh,
.page-module .sidebar-header,
.page-module > nav > :first-child {
  padding: 20px;
  border-bottom: 1px solid var(--glass-border);
}

.page-module .sb-head h2,
.page-module .sbh h2,
.page-module .sidebar-header h1,
.page-module > nav h2 {
  font-size: 1.05rem;
  color: var(--acc, var(--accent, var(--blue)));
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.page-module .sb-head p,
.page-module .sbh p,
.page-module .sidebar-header p {
  font-size: 0.8rem;
  color: var(--muted);
  margin-top: 3px;
}

/* Search input */
.page-module #search,
.page-module #q,
.page-module #search-box,
.page-module > nav input {
  width: 100%;
  padding: 8px 12px;
  background: rgba(13, 17, 23, 0.6);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--glass-border);
  border-radius: 8px;
  color: var(--text);
  font-size: 0.84rem;
  margin-top: 10px;
  transition: border-color var(--t-fast), box-shadow var(--t-fast);
}
.page-module > nav input {
  width: calc(100% - 32px);
  margin: 0 16px 12px;
}

.page-module #search:focus,
.page-module #q:focus,
.page-module #search-box:focus,
.page-module > nav input:focus {
  outline: none;
  border-color: var(--acc, var(--accent, var(--blue)));
  box-shadow: 0 0 12px rgba(88, 166, 255, 0.15);
}

/* Nav links */
.page-module .nav-list { list-style: none; padding: 6px 0; }
.page-module #nav { overflow-y: auto; flex: 1; padding: 6px 0 16px; }
.page-module .nav-section { padding: 8px 16px 4px; font-size: 0.68rem; font-weight: 700; letter-spacing: 0.08em; color: var(--muted); text-transform: uppercase; }
.page-module .nav-num { font-size: 0.72rem; color: var(--muted); min-width: 20px; }
.page-module .nav-list li a,
.page-module #nl li a,
.page-module .nav-item,
.page-module > nav a {
  display: block;
  padding: 7px 18px;
  color: var(--muted);
  text-decoration: none;
  font-size: 0.84rem;
  border-left: 3px solid transparent;
  transition: all var(--t-fast);
}
.page-module .nav-list li a:hover,
.page-module .nav-list li a.active,
.page-module #nl li a:hover,
.page-module #nl li a.active,
.page-module .nav-item:hover,
.page-module .nav-item.active,
.page-module > nav a:hover {
  color: var(--text);
  border-left-color: var(--acc, var(--accent, var(--blue)));
  background: rgba(255, 255, 255, 0.03);
}

/* --- Main content area -------------------------------------- */
.page-module .main,
.page-module > main,
.page-module #main {
  flex: 1;
  padding: 32px 40px;
  max-width: 900px;
  overflow-y: auto;
}
.page-module .content { max-width: 900px; margin: 0 auto; padding: 32px 32px 80px; }

/* Page title */
.page-module .pg-title,
.page-module .pt,
.page-module header h1 {
  font-size: 2rem;
  font-weight: 700;
  color: var(--acc, var(--accent, var(--blue)));
  margin-bottom: 6px;
}
.page-module header h1 span { color: var(--acc, var(--accent, var(--blue))); }

.page-module .pg-sub,
.page-module .ps,
.page-module header p {
  color: var(--muted);
  margin-bottom: 28px;
  margin-top: 6px;
}

.page-module header { margin-bottom: 32px; }

.page-module .badge {
  display: inline-block;
  padding: 3px 10px;
  border-radius: 20px;
  font-size: 0.75rem;
  font-weight: 600;
  background: rgba(88, 166, 255, 0.1);
  color: var(--acc, var(--accent, var(--blue)));
  border: 1px solid rgba(88, 166, 255, 0.2);
  margin-top: 8px;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}

/* --- Topic / Card sections ---------------------------------- */
/* Pattern A: .topic  |  Pattern C: .card */
.page-module .topic,
.page-module .card {
  background: var(--glass-bg);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--glass-border);
  border-radius: 12px;
  box-shadow: var(--glass-shadow), var(--glass-glow);
  margin-bottom: 16px;
  overflow: hidden;
  transition: border-color var(--t-fast);
  scroll-margin-top: 20px;
}

.page-module .topic:hover,
.page-module .card:hover {
  border-color: rgba(255, 255, 255, 0.1);
}

/* Topic headers */
.page-module .topic-header,
.page-module .th,
.page-module .card-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 14px 18px;
  cursor: pointer;
  user-select: none;
  background: rgba(255, 255, 255, 0.02);
  transition: background var(--t-fast);
  font-weight: 600;
}

.page-module .topic-header:hover,
.page-module .th:hover,
.page-module .card-header:hover {
  background: rgba(255, 255, 255, 0.05);
  color: var(--acc, var(--accent, var(--blue)));
}

.page-module .arrow {
  color: var(--acc, var(--accent, var(--muted)));
  transition: transform 0.25s var(--ease);
}
.page-module .arrow.open { transform: rotate(180deg); }

/* Topic body */
.page-module .topic-body,
.page-module .tb,
.page-module .card-body {
  padding: 18px;
  border-top: 1px solid var(--glass-border);
  background: rgba(10, 14, 23, 0.3);
}
/* Pattern A: .tb starts hidden, toggled with .open class */
.page-module .tb { display: none; }
.page-module .tb.open { display: block; }
/* Pandas: .topic-body has no outer padding (children handle it), visible by default */
.page-module .topic-body { padding: 0; }
.page-module .collapsed .topic-body { display: none; }

.page-module .desc,
.page-module .topic-desc {
  color: var(--muted);
  margin-bottom: 14px;
  line-height: 1.6;
  font-size: 0.92rem;
  padding: 14px 18px;
}
.page-module .topic-desc code {
  background: rgba(33,38,45,0.6);
  padding: 1px 5px;
  border-radius: 3px;
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--acc, var(--accent, #f78166));
}

/* Pandas-specific: chevron & collapsed */
.page-module .chevron { color: var(--muted); transition: transform 0.2s var(--ease); font-size: 0.75rem; }
.page-module .collapsed .chevron { transform: rotate(-90deg); }

/* Pandas-specific: topic sub-elements */
.page-module .topic-num { font-size:0.72rem; font-weight:700; color:var(--acc); background:rgba(255,255,255,0.06); border-radius:6px; padding:2px 8px; min-width:24px; text-align:center; }
.page-module .topic-title { font-size: 0.95rem; font-weight: 600; flex: 1; }
.page-module .topic-tag {
  font-size: 0.68rem;
  background: rgba(33,38,45,0.5);
  color: var(--muted);
  border: 1px solid var(--glass-border);
  border-radius: 20px; padding: 2px 8px;
  backdrop-filter: blur(4px); -webkit-backdrop-filter: blur(4px);
}

/* Pandas hero section */
.page-module .hero {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  padding: 32px 36px; margin-bottom: 32px;
  box-shadow: var(--glass-shadow), var(--glass-glow);
}
.page-module .hero h1 { font-size: 2rem; font-weight: 800; margin-bottom: 8px; }
.page-module .hero h1 span { color: var(--acc, var(--accent, var(--blue))); }
.page-module .hero p { color: var(--muted); font-size: 0.95rem; line-height: 1.6; }
.page-module .hero-stats { display: flex; gap: 16px; margin-top: 20px; flex-wrap: wrap; }
.page-module .stat {
  background: rgba(33,38,45,0.4);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--glass-border);
  border-radius: 8px; padding: 10px 18px; text-align: center;
}
.page-module .stat-n { font-size: 1.5rem; font-weight: 700; color: var(--green); }
.page-module .stat-l { font-size: 0.72rem; color: var(--muted); margin-top: 2px; }

/* Code label (Pandas pattern) */
.page-module .code-label {
  display: flex; justify-content: space-between; align-items: center;
  padding: 7px 14px;
  background: rgba(22,27,34,0.8);
  backdrop-filter: blur(8px); -webkit-backdrop-filter: blur(8px);
  border-top: 1px solid var(--glass-border);
  font-size: 0.78rem; color: var(--muted);
}

/* Output box (Pandas) */
.page-module .output-box {
  background: rgba(10,14,23,0.6);
  border-top: 1px solid var(--glass-border);
  padding: 12px 20px;
  font-family: var(--font-mono);
  font-size: 0.8rem; color: #adbac7;
  line-height: 1.7; white-space: pre; overflow-x: auto;
}
.page-module .output-label { font-size: 0.68rem; color: var(--muted); margin-bottom: 6px; font-family: var(--font); }

/* Cheatsheet table (Pandas) */
.page-module .cheatsheet { padding: 20px; }
.page-module .cheatsheet h3 { font-size: 0.88rem; color: var(--muted); margin-bottom: 14px; }
.page-module table { width: 100%; border-collapse: collapse; font-size: 0.85rem; }
.page-module th {
  text-align: left; padding: 8px 12px;
  background: rgba(33,38,45,0.5);
  color: var(--muted); font-size: 0.72rem;
  letter-spacing: 0.05em; text-transform: uppercase;
}
.page-module td { padding: 8px 12px; border-bottom: 1px solid var(--glass-border); }
.page-module td code {
  background: rgba(33,38,45,0.6); padding: 2px 6px; border-radius: 3px;
  font-family: var(--font-mono); font-size: 0.8rem; color: #79c0ff;
}
.page-module tr:hover td { background: rgba(255,255,255,0.02); }

/* --- Code blocks -------------------------------------------- */
.page-module .code-block,
.page-module .code-wrap {
  position: relative;
  border: 1px solid rgba(48, 54, 61, 0.5);
  border-radius: 10px;
  overflow: hidden;
  margin-bottom: 14px;
  box-shadow: inset 0 2px 8px rgba(0, 0, 0, 0.2);
}

.page-module .code-header,
.page-module .ch {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 7px 12px;
  background: rgba(22, 27, 34, 0.8);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border-bottom: 1px solid var(--glass-border);
  font-size: 0.78rem;
  color: var(--muted);
}

.page-module .code-header button,
.page-module .ch button {
  background: none;
  border: 1px solid var(--border);
  color: var(--muted);
  padding: 2px 9px;
  border-radius: 4px;
  cursor: pointer;
  font-size: 0.73rem;
  transition: all var(--t-fast);
}
.page-module .code-header button:hover,
.page-module .ch button:hover {
  color: var(--text);
  border-color: var(--acc, var(--accent, var(--blue)));
  box-shadow: 0 0 8px rgba(88, 166, 255, 0.2);
}

.page-module .copy-btn {
  position: absolute;
  top: 6px;
  right: 6px;
  padding: 3px 10px;
  background: rgba(48, 54, 61, 0.8);
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  color: #e6edf3;
  border: none;
  border-radius: 5px;
  font-size: 0.72rem;
  cursor: pointer;
  z-index: 10;
  transition: all var(--t-fast);
}
.page-module .copy-btn:hover {
  background: var(--acc, var(--accent, var(--blue)));
  color: #000;
  box-shadow: 0 0 12px rgba(88, 166, 255, 0.3);
}

.page-module pre { margin: 0; overflow-x: auto; }
.page-module pre code { font-size: 0.83rem; padding: 14px !important; font-family: var(--font-mono); line-height: 1.6; }
.page-module h4 { font-size: 0.85rem; color: var(--acc, var(--accent, var(--blue))); margin: 14px 0 6px; text-transform: uppercase; letter-spacing: 0.06em; }

/* --- Real-World boxes --------------------------------------- */
.page-module .rw-block,
.page-module .rw {
  background: rgba(13, 40, 24, 0.5);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(35, 134, 54, 0.3);
  border-radius: 10px;
  padding: 15px;
  margin-top: 10px;
  box-shadow: 0 0 20px rgba(63, 185, 80, 0.04), inset 0 1px 0 rgba(63, 185, 80, 0.06);
}

.page-module .rw-header,
.page-module .rh {
  font-weight: 700;
  color: var(--green);
  margin-bottom: 7px;
  font-size: 0.85rem;
  text-shadow: 0 0 20px rgba(63, 185, 80, 0.25);
}

.page-module .rw-desc,
.page-module .rd {
  color: #7ee787;
  font-size: 0.84rem;
  margin-bottom: 11px;
  line-height: 1.5;
}

/* --- Practice boxes ----------------------------------------- */
.page-module .practice {
  background: rgba(13, 27, 42, 0.5);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(56, 139, 253, 0.3);
  border-radius: 10px;
  padding: 15px;
  margin-top: 10px;
  box-shadow: 0 0 20px rgba(88, 166, 255, 0.04), inset 0 1px 0 rgba(88, 166, 255, 0.06);
}

.page-module .ph {
  font-weight: 700;
  color: var(--blue);
  margin-bottom: 7px;
  font-size: 0.85rem;
  text-shadow: 0 0 20px rgba(88, 166, 255, 0.25);
}

.page-module .pd {
  color: #79c0ff;
  font-size: 0.84rem;
  margin-bottom: 11px;
  line-height: 1.5;
}


/* =============================================================
   HOME PAGE
   ============================================================= */

.page-home {
  padding: 40px 20px 80px;
  max-width: 1100px;
  margin: 0 auto;
}

.page-home .hero { text-align: center; margin-bottom: 40px; }

.page-home .hero h1 {
  font-size: 2.8rem;
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 12px;
}
.page-home .hero h1 span {
  background: linear-gradient(135deg, #58a6ff, #c084fc, #f97316);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  filter: drop-shadow(0 0 25px rgba(88, 166, 255, 0.3));
}

.page-home .hero p {
  color: var(--muted);
  font-size: 1.1rem;
  max-width: 600px;
  margin: 0 auto 16px;
}

.page-home .hero-badges { display: flex; flex-wrap: wrap; justify-content: center; gap: 8px; }

.page-home .hero-badges span {
  padding: 4px 14px;
  font-size: 0.78rem;
  border-radius: 20px;
  background: rgba(88, 166, 255, 0.06);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  border: 1px solid rgba(88, 166, 255, 0.12);
  color: var(--muted);
  transition: all var(--t-fast);
}
.page-home .hero-badges span:hover {
  background: rgba(88, 166, 255, 0.12);
  border-color: rgba(88, 166, 255, 0.25);
  box-shadow: 0 0 12px rgba(88, 166, 255, 0.1);
  color: var(--text);
}

/* Progress bar */
.page-home .progress-wrap {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  padding: 18px 22px;
  margin-bottom: 32px;
  box-shadow: var(--glass-shadow), var(--glass-glow);
}
.page-home .progress-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 10px;
  font-size: 0.85rem;
}
.page-home .progress-track {
  background: rgba(33, 38, 45, 0.6);
  border-radius: 10px;
  height: 10px;
  overflow: hidden;
}
.page-home .progress-fill {
  height: 100%;
  border-radius: 10px;
  background: linear-gradient(90deg, #58a6ff, #c084fc, #f97316);
  box-shadow: 0 0 16px rgba(88, 166, 255, 0.4);
  transition: width 0.6s var(--ease);
}

/* Section labels */
.page-home .section-label {
  font-size: 0.8rem;
  text-transform: uppercase;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--muted);
  border-left: 3px solid rgba(88, 166, 255, 0.3);
  padding-left: 10px;
  margin: 36px 0 14px;
  text-shadow: 0 0 20px rgba(88, 166, 255, 0.1);
}

/* Card grid */
.page-home .grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 18px;
}

/* Staggered card fade-in */
@keyframes card-in {
  from { opacity: 0; transform: translateY(24px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* Module cards */
.page-home .card {
  display: flex;
  flex-direction: column;
  padding: 22px;
  border-radius: 14px;
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  box-shadow: var(--glass-shadow), var(--glass-glow);
  text-decoration: none;
  color: inherit;
  position: relative;
  overflow: hidden;
  transition: transform var(--t-smooth), box-shadow var(--t-smooth), border-color var(--t-smooth);
  animation: card-in 0.5s var(--ease) both;
  will-change: transform;
}

/* Glowing top accent line */
.page-home .card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: linear-gradient(90deg, transparent, var(--accent-color, #58a6ff), transparent);
  opacity: 0.6;
  transition: all var(--t-fast);
}

.page-home .card:hover {
  transform: translateY(-4px);
  box-shadow: var(--glass-shadow-hover), var(--glass-glow), 0 0 20px rgba(88, 166, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.1);
}
.page-home .card:hover::before {
  height: 3px;
  opacity: 1;
  box-shadow: 0 0 15px var(--accent-color, #58a6ff);
}

.page-home .card.done { opacity: 0.6; }
.page-home .card.done::after {
  content: '\2713';
  position: absolute;
  top: 10px; right: 12px;
  background: var(--green);
  color: #000;
  font-size: 0.7rem;
  font-weight: 700;
  width: 20px; height: 20px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
}
.page-home .card.coming {
  opacity: 0.4;
  pointer-events: none;
  filter: saturate(0.3);
}

/* Card interior */
.page-home .card-top {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  margin-bottom: 12px;
}
.page-home .card-icon {
  width: 44px; height: 44px;
  border-radius: 10px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.4rem;
  flex-shrink: 0;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}
.page-home .card-meta { flex: 1; }
.page-home .card-num { font-size: 0.72rem; color: var(--muted); font-weight: 600; text-transform: uppercase; letter-spacing: 0.08em; }
.page-home .card-title { font-size: 1.1rem; font-weight: 700; line-height: 1.3; margin-top: 2px; }
.page-home .card-desc { font-size: 0.85rem; color: var(--muted); line-height: 1.55; margin-bottom: 14px; }
.page-home .card-tags { display: flex; flex-wrap: wrap; gap: 6px; }
.page-home .tag {
  padding: 2px 9px;
  border-radius: 12px;
  font-size: 0.72rem;
  font-weight: 600;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}
.page-home .card-footer {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-top: 16px;
  padding-top: 14px;
  border-top: 1px solid var(--glass-border);
}
.page-home .card-stats { font-size: 0.75rem; color: var(--muted); }
.page-home .card-arrow { color: var(--accent-color); font-size: 1rem; transition: transform var(--t-fast); }
.page-home .card:hover .card-arrow { transform: translateX(3px); }

/* Progress wrap extras */
.page-home .progress-wrap h3 {
  font-size: 0.9rem;
  color: var(--muted);
  margin-bottom: 10px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
}
.page-home .progress-label { font-size: 0.8rem; color: var(--muted); margin-top: 6px; }

/* Container */
.page-home .container { max-width: 1100px; margin: 0 auto; }

/* Footer */
.page-home footer { text-align: center; color: var(--muted); font-size: 0.82rem; margin-top: 56px; }
.page-home footer a { color: var(--blue); text-decoration: none; }
.page-home footer a:hover { text-decoration: underline; }


/* =============================================================
   OVERVIEW PAGE
   ============================================================= */

.page-overview {
  padding: 40px 20px 80px;
  max-width: 1140px;
  margin: 0 auto;
}

/* Navigation bar */
.page-overview .nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 48px;
}
.page-overview .nav-back {
  display: flex;
  align-items: center;
  gap: 6px;
  color: var(--muted);
  font-size: 0.85rem;
  text-decoration: none;
  padding: 6px 14px;
  background: rgba(22, 27, 34, 0.4);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  border: 1px solid var(--glass-border);
  border-radius: 8px;
  transition: all var(--t-fast);
}
.page-overview .nav-back:hover {
  color: var(--blue);
  border-color: rgba(88, 166, 255, 0.3);
  box-shadow: 0 0 12px rgba(88, 166, 255, 0.1);
}
.page-overview .nav-title {
  font-size: 0.9rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
}

/* Hero */
.page-overview .hero { text-align: center; margin-bottom: 48px; }
.page-overview .hero h1 {
  font-size: 3rem;
  font-weight: 800;
  line-height: 1.1;
  margin-bottom: 14px;
}
.page-overview .hero h1 em {
  font-style: normal;
  background: linear-gradient(90deg, #58a6ff, #c084fc, #f97316);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  filter: drop-shadow(0 0 25px rgba(88, 166, 255, 0.3));
}
.page-overview .hero p {
  color: var(--muted);
  font-size: 1.05rem;
  max-width: 600px;
  margin: 0 auto;
}

/* Stats row */
.page-overview .stats-row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 16px;
  margin-bottom: 48px;
}
.page-overview .stat-box {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  padding: 20px;
  text-align: center;
  box-shadow: var(--glass-shadow), var(--glass-glow);
  transition: transform var(--t-fast), box-shadow var(--t-fast);
}
.page-overview .stat-box:hover {
  transform: translateY(-2px);
  box-shadow: var(--glass-shadow-hover);
}
.page-overview .stat-box .num {
  font-size: 2rem;
  font-weight: 800;
  display: block;
  text-shadow: 0 0 25px currentColor;
}
.page-overview .stat-box .label {
  font-size: 0.82rem;
  color: var(--muted);
  margin-top: 4px;
}
.page-overview .stat-box.c1 .num { color: var(--blue); }
.page-overview .stat-box.c2 .num { color: var(--green); }
.page-overview .stat-box.c3 .num { color: var(--purple); }
.page-overview .stat-box.c4 .num { color: var(--orange); }

/* Phase heads */
.page-overview .phase-head {
  display: flex;
  align-items: center;
  gap: 16px;
  margin: 36px 0 20px;
}
.page-overview .phase-num {
  width: 36px; height: 36px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700;
  font-size: 0.85rem;
  flex-shrink: 0;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  box-shadow: 0 0 12px rgba(255, 255, 255, 0.04);
}
.page-overview .phase-title { font-weight: 700; font-size: 1.1rem; }
.page-overview .phase-desc { color: var(--muted); font-size: 0.85rem; margin-top: 2px; }
.page-overview .phase-line {
  flex: 1;
  height: 1px;
  background: linear-gradient(90deg, var(--glass-border), transparent);
}

/* Phase color variants */
.page-overview .p1 .phase-num { background: rgba(88,166,255,.15); color: #58a6ff; border: 1px solid rgba(88,166,255,.3); }
.page-overview .p2 .phase-num { background: rgba(192,132,252,.15); color: #c084fc; border: 1px solid rgba(192,132,252,.3); }
.page-overview .p3 .phase-num { background: rgba(52,211,153,.15); color: #34d399; border: 1px solid rgba(52,211,153,.3); }
.page-overview .p4 .phase-num { background: rgba(249,115,22,.15); color: #f97316; border: 1px solid rgba(249,115,22,.3); }
.page-overview .p5 .phase-num { background: rgba(74,222,128,.15); color: #4ade80; border: 1px solid rgba(74,222,128,.3); }

/* Roadmap card grid */
.page-overview .roadmap {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 18px;
  margin-bottom: 12px;
}
.page-overview .roadmap.cols3 { grid-template-columns: repeat(3, 1fr); }

/* Roadmap cards */
.page-overview .rm-card {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  box-shadow: var(--glass-shadow), var(--glass-glow);
  transition: transform var(--t-smooth), box-shadow var(--t-smooth), border-color var(--t-smooth);
  position: relative;
}
/* Glowing top accent */
.page-overview .rm-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
}
.page-overview .rm-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--glass-shadow-hover), var(--glass-glow), 0 0 20px rgba(88, 166, 255, 0.06);
  border-color: rgba(255, 255, 255, 0.1);
}

.page-overview .rm-card-top { padding: 20px 20px 0; flex: 1; }
.page-overview .rm-meta {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  margin-bottom: 12px;
}
.page-overview .rm-icon {
  width: 46px; height: 46px;
  border-radius: 11px;
  display: flex; align-items: center; justify-content: center;
  font-size: 1.5rem;
  flex-shrink: 0;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
}
.page-overview .rm-title { font-size: 1.05rem; font-weight: 700; }
.page-overview .rm-desc { color: var(--muted); font-size: 0.82rem; line-height: 1.55; margin: 0 22px 14px; }
.page-overview .rm-skills { display: flex; flex-wrap: wrap; gap: 6px; margin: 0 22px 14px; }
.page-overview .skill {
  font-size: 0.68rem;
  padding: 3px 9px;
  border-radius: 6px;
  backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  transition: all var(--t-fast);
}
.page-overview .skill:hover { box-shadow: 0 0 8px rgba(255, 255, 255, 0.04); }

/* Card footer */
.page-overview .rm-footer {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 12px 18px;
  border-top: 1px solid var(--glass-border);
  background: rgba(10, 14, 23, 0.3);
}
.page-overview .rm-stats { font-size: 0.73rem; color: var(--muted); }
.page-overview .rm-link {
  font-size: 0.75rem;
  padding: 5px 12px;
  border-radius: 6px;
  font-weight: 600;
  transition: all var(--t-fast);
}
.page-overview .rm-link:hover {
  box-shadow: 0 0 12px rgba(255, 255, 255, 0.08);
  transform: translateX(2px);
}

/* Flow diagram */
.page-overview .flow-wrap {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 16px;
  padding: 32px;
  margin: 36px 0;
  box-shadow: var(--glass-shadow);
  overflow-x: auto;
}
.page-overview .flow-title { font-size: 1.1rem; font-weight: 700; margin-bottom: 20px; text-align: center; }
.page-overview .flow { display: flex; align-items: flex-start; gap: 10px; min-width: 700px; }
.page-overview .flow-col { display: flex; flex-direction: column; gap: 8px; flex: 1; }
.page-overview .flow-label {
  font-size: 0.65rem;
  text-transform: uppercase;
  letter-spacing: 0.1em;
  color: var(--muted);
  text-align: center;
  margin-bottom: 4px;
}
.page-overview .flow-node {
  padding: 10px 14px;
  border-radius: 10px;
  font-size: 0.78rem;
  font-weight: 600;
  text-align: center;
  cursor: pointer;
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  transition: transform 0.15s, box-shadow 0.15s;
}
.page-overview .flow-node:hover {
  transform: scale(1.06);
  box-shadow: 0 0 15px rgba(255, 255, 255, 0.08);
}
.page-overview .flow-arrow {
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.2rem;
  color: var(--muted);
  padding-top: 20px;
}

/* Career cards */
.page-overview .careers {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px;
  margin-top: 20px;
}
.page-overview .career-card {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  padding: 20px;
  box-shadow: var(--glass-shadow), var(--glass-glow);
  position: relative;
  overflow: hidden;
}
.page-overview .career-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 3px;
}
/* Career card content — matches overview.html class names */
.page-overview .career-title { font-weight: 700; font-size: 1rem; margin-bottom: 8px; }
.page-overview .career-card h3 { font-size: 1rem; font-weight: 700; margin-bottom: 6px; display: flex; align-items: center; gap: 8px; }
.page-overview .career-card p { font-size: 0.8rem; color: var(--muted); margin-bottom: 14px; line-height: 1.55; }
.page-overview .career-modules { display: flex; flex-direction: column; gap: 5px; }
.page-overview .career-module { display: flex; align-items: center; gap: 8px; font-size: 0.75rem; color: var(--muted); }
.page-overview .career-module::before { content: '\2192'; color: var(--green); font-weight: 700; }
.page-overview .career-mods { font-size: 0.8rem; color: var(--muted); line-height: 1.7; }
.page-overview .career-mods span { color: var(--green); }

/* Prereq badges */
.page-overview .prereq-row { margin: 0 22px 14px; display: flex; align-items: center; gap: 6px; }
.page-overview .prereq-label { font-size: 0.68rem; color: var(--muted); font-weight: 600; text-transform: uppercase; letter-spacing: 0.06em; }
.page-overview .prereq-badge {
  font-size: 0.67rem; font-weight: 600; padding: 2px 8px; border-radius: 8px;
  background: rgba(88,166,255,0.1); color: var(--blue); border: 1px solid rgba(88,166,255,0.2);
  backdrop-filter: blur(4px); -webkit-backdrop-filter: blur(4px);
}

/* Hero label */
.page-overview .hero-label {
  display: inline-block; font-size: 0.72rem; font-weight: 700; letter-spacing: 0.12em;
  text-transform: uppercase; color: var(--blue);
  background: rgba(88,166,255,0.06); backdrop-filter: blur(6px); -webkit-backdrop-filter: blur(6px);
  border: 1px solid rgba(88,166,255,0.15); padding: 4px 14px; border-radius: 20px; margin-bottom: 16px;
}

/* Stat box .lbl alias */
.page-overview .stat-box .lbl { font-size: 0.82rem; color: var(--muted); margin-top: 4px; }

/* Phase info (used in overview.html instead of .phase-title / .phase-desc) */
.page-overview .phase-info h2 { font-size: 1.3rem; font-weight: 700; }
.page-overview .phase-info p { font-size: 0.83rem; color: var(--muted); margin-top: 3px; }

/* Rm-card content used in overview */
.page-overview .rm-num { font-size: 0.7rem; color: var(--muted); font-weight: 600; text-transform: uppercase; letter-spacing: 0.08em; }

/* Skill badges (inline styles handle colors, just need base) */
.page-overview .skill { font-weight: 600; }

/* Flow diagram classes from overview.html */
.page-overview .flow-col-label {
  font-size: 0.65rem; color: var(--muted); font-weight: 700;
  text-transform: uppercase; letter-spacing: 0.1em; text-align: center; margin-bottom: 4px;
}
.page-overview .flow-wrap h2 {
  font-size: 1.1rem; font-weight: 700; margin-bottom: 28px;
  display: flex; align-items: center; gap: 10px;
}
.page-overview .flow-wrap h2 span { font-size: 0.72rem; color: var(--muted); font-weight: 400; }
.page-overview .flow-col { display: flex; flex-direction: column; gap: 10px; }
.page-overview .flow-arrow {
  display: flex; align-items: center; padding: 0 6px;
  color: var(--muted); font-size: 1.1rem; align-self: center; flex-shrink: 0;
}

/* Tips */
.page-overview .tips {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px;
  margin-top: 20px;
}
.page-overview .tip-box {
  background: var(--glass-bg);
  backdrop-filter: blur(var(--glass-blur));
  -webkit-backdrop-filter: blur(var(--glass-blur));
  border: 1px solid var(--glass-border);
  border-radius: 14px;
  padding: 20px 22px;
  box-shadow: var(--glass-shadow), var(--glass-glow);
}
.page-overview .tip-box h3,
.page-overview .tip-box h4 { font-size: 0.9rem; font-weight: 700; margin-bottom: 8px; display: flex; align-items: center; gap: 8px; }
.page-overview .tip-box p,
.page-overview .tip-box li { font-size: 0.82rem; color: var(--muted); line-height: 1.65; }
.page-overview .tip-box ul { padding-left: 16px; }

/* Container */
.page-overview .container { max-width: 1140px; margin: 0 auto; }

/* Footer */
.page-overview footer { text-align: center; color: var(--muted); font-size: 0.82rem; padding-top: 24px; border-top: 1px solid var(--glass-border); }
.page-overview footer a { color: var(--blue); text-decoration: none; }
.page-overview footer a:hover { text-decoration: underline; }

/* Section headers for overview */
.page-overview h2 { font-size: 1.3rem; margin: 40px 0 16px; }


/* =============================================================
   PRACTICE CHECKLIST (todos)
   ============================================================= */

.page-module .todo-list {
  background: rgba(10, 20, 35, 0.55);
  backdrop-filter: blur(10px);
  -webkit-backdrop-filter: blur(10px);
  border: 1px solid rgba(100, 220, 180, 0.22);
  border-radius: 10px;
  padding: 14px 16px;
  margin-top: 10px;
  box-shadow: 0 0 18px rgba(100, 220, 180, 0.05), inset 0 1px 0 rgba(100, 220, 180, 0.07);
}

.page-module .todo-head {
  font-weight: 700;
  color: #64dcb4;
  font-size: 0.85rem;
  margin-bottom: 10px;
  text-shadow: 0 0 16px rgba(100, 220, 180, 0.3);
}

.page-module .todo-list ul {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 7px;
}

.page-module .todo-list li label {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  color: #b3e8d8;
  font-size: 0.83rem;
  line-height: 1.5;
  cursor: pointer;
  transition: color 0.2s;
}

.page-module .todo-list li label:hover {
  color: #e0fff5;
}

.page-module .todo-list input[type="checkbox"] {
  appearance: none;
  -webkit-appearance: none;
  width: 16px;
  height: 16px;
  min-width: 16px;
  border: 1px solid rgba(100, 220, 180, 0.45);
  border-radius: 4px;
  background: rgba(100, 220, 180, 0.06);
  cursor: pointer;
  margin-top: 2px;
  position: relative;
  transition: all 0.2s;
}

.page-module .todo-list input[type="checkbox"]:checked {
  background: rgba(100, 220, 180, 0.25);
  border-color: #64dcb4;
}

.page-module .todo-list input[type="checkbox"]:checked::after {
  content: "✓";
  position: absolute;
  top: -1px;
  left: 2px;
  color: #64dcb4;
  font-size: 12px;
  font-weight: 700;
}

.page-module .todo-list li label:has(input:checked) {
  color: rgba(179, 232, 216, 0.45);
  text-decoration: line-through;
  text-decoration-color: rgba(100, 220, 180, 0.4);
}

/* =============================================================
   RESPONSIVE — mobile-first breakpoints
   1024px  tablet landscape
    860px  tablet portrait / small laptop
    700px  large phone landscape
    600px  phone (iPhone Plus, Android large)
    430px  iPhone 14 Pro / standard phones
    375px  iPhone SE / small phones
   ============================================================= */

/* ── 1024px: tablet landscape ─────────────────────────────── */
@media (max-width: 1024px) {
  .page-home { padding: 32px 16px 60px; }
  .page-home .grid { grid-template-columns: repeat(auto-fill, minmax(260px, 1fr)); }
  .page-overview .container { padding: 0 16px; }
  .page-overview .flow { gap: 8px; }
  .page-overview .flow-arrow { font-size: 1.2rem; }
}

/* ── 860px: tablet portrait ───────────────────────────────── */
@media (max-width: 860px) {
  /* Overview */
  .page-overview .stats-row { grid-template-columns: repeat(2, 1fr); }
  .page-overview .roadmap,
  .page-overview .roadmap.cols3 { grid-template-columns: 1fr; }
  .page-overview .careers { grid-template-columns: 1fr 1fr; }
  .page-overview .tips { grid-template-columns: 1fr 1fr; }
  .page-overview .hero h1 { font-size: 2.2rem; }
  .page-overview .flow { flex-wrap: wrap; justify-content: center; }
  .page-overview .flow-arrow { display: none; }
  .page-overview .flow > div { min-width: 140px; }

  /* Home */
  .page-home { padding: 28px 16px 60px; }
  .page-home .hero h1 { font-size: 2.4rem; }
  .page-home .grid { grid-template-columns: repeat(auto-fill, minmax(240px, 1fr)); gap: 14px; }

  /* Module pages */
  .page-module .sidebar,
  .page-module > nav { width: 220px; }
  .page-module .main,
  .page-module > main { padding: 24px 20px; }
}

/* ── 700px: large phone landscape / small tablet ──────────── */
@media (max-width: 700px) {
  /* Module: hide sidebar, go single column */
  .page-module .sidebar,
  .page-module > nav,
  .page-module #sidebar { display: none; }
  .page-module .main,
  .page-module > main,
  .page-module #main { padding: 16px 14px; max-width: 100%; }
  .page-module { display: block; }
  .page-module .content { padding: 16px 14px 60px; }

  /* Module: topic cards */
  .page-module .topic,
  .page-module .card { margin-bottom: 12px; }
  .page-module .tb, .page-module .card-body { padding: 14px; }
  .page-module .code-block pre { font-size: 0.78rem; }

  /* Home */
  .page-home .hero h1 { font-size: 2rem; }
  .page-home .hero p { font-size: 1rem; }
  .page-home .grid { grid-template-columns: 1fr 1fr; gap: 12px; }
  .page-home .card { padding: 16px; }
  .page-home .card-icon { font-size: 1.4rem; width: 40px; height: 40px; }
  .page-home .card-title { font-size: 0.95rem; }
  .page-home .card-desc { font-size: 0.82rem; }
  .page-home .card-tags { display: none; }

  /* Overview */
  .page-overview .hero h1 { font-size: 1.9rem; }
  .page-overview .stats-row { grid-template-columns: repeat(2, 1fr); gap: 10px; }
  .page-overview .stat-box { padding: 16px 12px; }
  .page-overview .stat-box .num { font-size: 1.8rem; }
  .page-overview .careers { grid-template-columns: 1fr; }
  .page-overview .tips { grid-template-columns: 1fr; }

  /* Site nav */
  .site-nav { padding: 10px 14px; margin-bottom: 20px; }
  .site-nav-logo { font-size: 0.9rem; }
  .site-nav-link { padding: 5px 12px; font-size: 0.82rem; }
}

/* ── 600px: standard phones ───────────────────────────────── */
@media (max-width: 600px) {
  /* Home: single column cards */
  .page-home { padding: 16px 12px 60px; }
  .page-home .hero { margin-bottom: 24px; }
  .page-home .hero h1 { font-size: 1.85rem; }
  .page-home .hero p { font-size: 0.95rem; }
  .page-home .hero-badges { gap: 6px; }
  .page-home .hero-badges span { font-size: 0.73rem; padding: 4px 10px; }
  .page-home .grid { grid-template-columns: 1fr; gap: 12px; }
  .page-home .card { padding: 16px 14px; }
  .page-home .card-tags { display: flex; flex-wrap: wrap; }
  .page-home .card-stats { font-size: 0.75rem; }
  .page-home .progress-wrap { padding: 14px 16px; }
  .page-home .section-label { margin: 24px 0 10px; }

  /* Overview */
  .page-overview .hero h1 { font-size: 1.7rem; }
  .page-overview .hero p { font-size: 0.95rem; }
  .page-overview .stats-row { grid-template-columns: 1fr 1fr; gap: 8px; }
  .page-overview .rm-card { padding: 16px; }
  .page-overview .phase-head { padding: 14px 16px; gap: 12px; }
  .page-overview .phase-num { width: 36px; height: 36px; font-size: 1rem; }

  /* Site nav: stack vertically */
  .site-nav { flex-direction: column; align-items: flex-start; gap: 10px; padding: 12px 14px; }
  .site-nav-links { width: 100%; justify-content: flex-start; }
  .site-nav-link { flex: 1; text-align: center; }
}

/* ── 430px: iPhone 14 Pro / most modern phones ────────────── */
@media (max-width: 430px) {
  .page-home .hero h1 { font-size: 1.65rem; }
  .page-home .card-icon { display: none; }
  .page-home .card-num { font-size: 0.7rem; }
  .page-home .card-title { font-size: 0.9rem; }
  .page-home .card-footer { flex-direction: column; align-items: flex-start; gap: 4px; }
  .page-home .card-arrow { display: none; }

  .page-overview .hero h1 { font-size: 1.5rem; }
  .page-overview .stats-row { grid-template-columns: 1fr 1fr; }
  .page-overview .stat-box .num { font-size: 1.5rem; }
  .page-overview .flow-col { gap: 6px; }
  .page-overview .flow-node { padding: 8px 10px; font-size: 0.78rem; }

  /* Module pages: tighter */
  .page-module .pg-title,
  .page-module .pt,
  .page-module header h1 { font-size: 1.5rem; }
  .page-module .th,
  .page-module .card-header { font-size: 0.9rem; padding: 12px 14px; }
  .page-module .tb,
  .page-module .card-body { padding: 12px; }
  .page-module .rw,
  .page-module .practice,
  .page-module .todo-list { padding: 12px; }
  .page-module .code-block pre { font-size: 0.75rem; overflow-x: auto; }
}

/* ── 375px: iPhone SE / small budget phones ───────────────── */
@media (max-width: 375px) {
  .page-home { padding: 12px 10px 50px; }
  .page-home .hero h1 { font-size: 1.5rem; }
  .page-home .card { padding: 12px; }
  .page-overview .hero h1 { font-size: 1.35rem; }
  .page-overview .stats-row { grid-template-columns: 1fr 1fr; gap: 6px; }
  .site-nav-link { padding: 5px 8px; font-size: 0.78rem; }
}

/* ── Touch: disable tilt effect on touch devices ─────────── */
@media (hover: none) and (pointer: coarse) {
  .page-home .card { transform: none !important; }
  .page-home .card:active {
    transform: scale(0.97) !important;
    transition: transform 0.1s;
  }
}

/* ── Site Nav (shared across home & overview) ──────────────── */
.site-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 20px;
  margin-bottom: 32px;
  background: rgba(22, 27, 34, 0.55);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(255,255,255,0.07);
  border-radius: 14px;
}
.site-nav-logo {
  font-weight: 700;
  font-size: 1rem;
  color: var(--text);
  text-decoration: none;
  letter-spacing: 0.01em;
}
.site-nav-logo:hover { color: var(--acc, #58a6ff); }
.site-nav-links {
  display: flex;
  gap: 6px;
}
.site-nav-link {
  padding: 6px 16px;
  border-radius: 8px;
  font-size: 0.875rem;
  font-weight: 500;
  color: var(--muted);
  text-decoration: none;
  transition: all 0.2s;
}
.site-nav-link:hover {
  color: var(--text);
  background: rgba(255,255,255,0.06);
}
.site-nav-link.active {
  color: var(--text);
  background: rgba(88,166,255,0.12);
  border: 1px solid rgba(88,166,255,0.25);
}
@media (max-width: 480px) {
  .site-nav { flex-direction: column; gap: 10px; }
}

/* ── Scroll Progress Bar ───────────────────────────────────── */
#scroll-progress {
  position: fixed;
  top: 0; left: 0;
  height: 3px;
  width: 0%;
  background: linear-gradient(90deg, #58a6ff, #c084fc, #f97316);
  z-index: 9999;
  transition: width 0.1s linear;
  box-shadow: 0 0 8px rgba(88,166,255,0.6);
}

/* ── Ripple click effect ────────────────────────────────────── */
.ripple-wave {
  position: absolute;
  border-radius: 50%;
  background: rgba(255,255,255,0.12);
  transform: scale(0);
  animation: ripple-anim 0.6s linear;
  pointer-events: none;
  z-index: 10;
}
@keyframes ripple-anim {
  to { transform: scale(4); opacity: 0; }
}

/* ── Star/particle canvas (behind everything) ──────────────── */
#star-canvas {
  position: fixed;
  inset: 0;
  z-index: 0;
  pointer-events: none;
  opacity: 0.5;
}

/* ── Typing cursor on hero ──────────────────────────────────── */
.typing-cursor {
  display: inline-block;
  width: 3px;
  height: 1em;
  background: var(--acc, #58a6ff);
  margin-left: 3px;
  vertical-align: middle;
  animation: blink 1s step-end infinite;
}
@keyframes blink {
  0%, 100% { opacity: 1; }
  50%       { opacity: 0; }
}

/* ── Glow pulse on section labels ──────────────────────────── */
@keyframes label-glow {
  0%, 100% { box-shadow: 0 0 0 rgba(88,166,255,0); }
  50%       { box-shadow: 0 0 18px rgba(88,166,255,0.18); }
}
.page-home .section-label {
  animation: label-glow 4s ease-in-out infinite;
}

/* ── Mobile hamburger menu ──────────────────────────────────── */
.mob-menu-btn {
  display: none;
  position: fixed;
  bottom: 20px;
  right: 20px;
  z-index: 200;
  width: 48px;
  height: 48px;
  border-radius: 50%;
  background: rgba(22,27,34,0.9);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(88,166,255,0.3);
  color: var(--text);
  font-size: 1.3rem;
  cursor: pointer;
  box-shadow: 0 4px 20px rgba(0,0,0,0.4), 0 0 12px rgba(88,166,255,0.15);
  transition: transform 0.2s, box-shadow 0.2s;
  align-items: center;
  justify-content: center;
}
.mob-menu-btn:hover {
  transform: scale(1.08);
  box-shadow: 0 6px 24px rgba(0,0,0,0.5), 0 0 18px rgba(88,166,255,0.25);
}

/* Sidebar overlay on mobile */
.page-module .sidebar.mob-open,
.page-module > nav.mob-open,
.page-module #sidebar.mob-open {
  display: flex !important;
  flex-direction: column;
  position: fixed !important;
  top: 0; left: 0;
  width: 280px !important;
  height: 100vh;
  z-index: 150;
  animation: slide-in 0.28s var(--ease);
}
@keyframes slide-in {
  from { transform: translateX(-100%); opacity: 0; }
  to   { transform: translateX(0);    opacity: 1; }
}

/* Dim overlay behind open sidebar */
.mob-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.55);
  z-index: 140;
  backdrop-filter: blur(2px);
}
.mob-overlay.active { display: block; }

@media (max-width: 700px) {
  .mob-menu-btn { display: flex; }
}

/* Prevent body scroll when sidebar open on mobile */
body.mob-sidebar-open { overflow: hidden; }

/* ── Safe area insets for iPhone notch / home bar ──────────── */
@supports (padding: max(0px)) {
  .page-home  { padding-bottom: max(80px, env(safe-area-inset-bottom)); }
  .mob-menu-btn { bottom: max(20px, env(safe-area-inset-bottom)); right: max(20px, env(safe-area-inset-right)); }
}

/* ── Page transition ────────────────────────────────────────── */
@keyframes page-fade-in {
  from { opacity: 0; transform: translateY(10px); }
  to   { opacity: 1; transform: translateY(0); }
}
@keyframes page-fade-out {
  from { opacity: 1; transform: translateY(0); }
  to   { opacity: 0; transform: translateY(-8px); }
}
body.page-transitioning { animation: page-fade-out 0.25s var(--ease) forwards; }
body { animation: page-fade-in 0.35s var(--ease) both; }

/* ── Loading screen ─────────────────────────────────────────── */
#page-loader {
  position: fixed;
  inset: 0;
  background: var(--bg);
  z-index: 9000;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 20px;
  transition: opacity 0.5s var(--ease), visibility 0.5s;
}
#page-loader.hidden {
  opacity: 0;
  visibility: hidden;
  pointer-events: none;
}
.loader-logo {
  font-size: 2.8rem;
  animation: loader-pulse 1.2s ease-in-out infinite;
}
@keyframes loader-pulse {
  0%, 100% { transform: scale(1);    filter: drop-shadow(0 0 0px rgba(88,166,255,0)); }
  50%       { transform: scale(1.12); filter: drop-shadow(0 0 18px rgba(88,166,255,0.6)); }
}
.loader-bar-wrap {
  width: 180px;
  height: 3px;
  background: rgba(255,255,255,0.07);
  border-radius: 4px;
  overflow: hidden;
}
.loader-bar {
  height: 100%;
  background: linear-gradient(90deg, #58a6ff, #c084fc, #f97316);
  border-radius: 4px;
  animation: loader-fill 0.9s var(--ease) forwards;
}
@keyframes loader-fill {
  from { width: 0%; }
  to   { width: 100%; }
}
.loader-text {
  font-size: 0.8rem;
  color: var(--muted);
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

/* ── Confetti canvas ────────────────────────────────────────── */
#confetti-canvas {
  position: fixed;
  inset: 0;
  z-index: 8000;
  pointer-events: none;
}

/* ── Completion modal ───────────────────────────────────────── */
#complete-modal {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 8500;
  align-items: center;
  justify-content: center;
  background: rgba(0,0,0,0.6);
  backdrop-filter: blur(8px);
  animation: page-fade-in 0.3s var(--ease);
}
#complete-modal.show { display: flex; }
.complete-card {
  background: var(--glass-bg);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid rgba(88,166,255,0.25);
  border-radius: 20px;
  padding: 40px 48px;
  text-align: center;
  max-width: 420px;
  width: 90%;
  box-shadow: 0 24px 80px rgba(0,0,0,0.5), 0 0 40px rgba(88,166,255,0.12);
  animation: card-in 0.4s var(--ease) 0.1s both;
}
.complete-emoji { font-size: 3.5rem; margin-bottom: 12px; }
.complete-card h2 { font-size: 1.6rem; font-weight: 800; margin-bottom: 8px;
  background: linear-gradient(135deg, #58a6ff, #c084fc);
  -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.complete-card p  { color: var(--muted); font-size: 0.95rem; margin-bottom: 24px; }
.complete-close {
  padding: 10px 28px;
  border-radius: 10px;
  background: linear-gradient(135deg, rgba(88,166,255,0.2), rgba(192,132,252,0.2));
  border: 1px solid rgba(88,166,255,0.3);
  color: var(--text);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
}
.complete-close:hover { background: linear-gradient(135deg, rgba(88,166,255,0.35), rgba(192,132,252,0.35)); transform: translateY(-1px); }

/* ============================================================
   NAV-UX: Back-to-top, Breadcrumb, Reading time,
           Keyboard shortcuts
   ============================================================ */

/* ── Back to top button ─────────────────────────────────────── */
#back-to-top {
  position: fixed;
  bottom: 80px;
  right: 20px;
  z-index: 190;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: rgba(22,27,34,0.88);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(88,166,255,0.25);
  color: var(--text);
  font-size: 1.1rem;
  font-weight: 700;
  cursor: pointer;
  box-shadow: 0 4px 18px rgba(0,0,0,0.4);
  opacity: 0;
  visibility: hidden;
  transform: translateY(12px);
  transition: opacity 0.3s, transform 0.3s, visibility 0.3s, box-shadow 0.2s;
  display: flex;
  align-items: center;
  justify-content: center;
}
#back-to-top.visible {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}
#back-to-top:hover {
  box-shadow: 0 6px 24px rgba(88,166,255,0.25);
  border-color: rgba(88,166,255,0.5);
  transform: translateY(-2px);
}
body.light-mode #back-to-top {
  background: rgba(255,255,255,0.9);
  color: #1a2030;
}

/* ── Breadcrumb ─────────────────────────────────────────────── */
#breadcrumb {
  display: flex;
  align-items: center;
  gap: 6px;
  flex-wrap: wrap;
  padding: 8px 14px;
  margin-bottom: 20px;
  background: rgba(22,27,34,0.4);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border: 1px solid var(--glass-border);
  border-radius: 10px;
  font-size: 0.8rem;
  color: var(--muted);
  animation: card-in 0.4s var(--ease) 0.1s both;
}
#breadcrumb a {
  color: var(--blue);
  text-decoration: none;
  transition: color 0.2s;
}
#breadcrumb a:hover { color: var(--text); text-decoration: underline; }
.bc-sep { color: var(--muted); opacity: 0.5; }
.bc-module { color: var(--muted); }
#bc-topic {
  color: var(--text);
  font-weight: 600;
  max-width: 260px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  transition: color 0.2s;
}
body.light-mode #breadcrumb { background: rgba(255,255,255,0.6); }

/* ── Reading time badge ─────────────────────────────────────── */
.read-time {
  margin-left: auto;
  font-size: 0.72rem;
  font-weight: 500;
  color: var(--muted);
  background: rgba(88,166,255,0.08);
  border: 1px solid rgba(88,166,255,0.15);
  border-radius: 20px;
  padding: 2px 9px;
  white-space: nowrap;
  transition: opacity 0.2s;
}
.th .read-time,
.card-header .read-time {
  flex-shrink: 0;
}
/* Make the .th a flex row so read-time sits on the right */
.page-module .th,
.page-module .card-header {
  display: flex;
  align-items: center;
  gap: 8px;
}
.page-module .th .arr,
.page-module .card-header .arrow {
  margin-left: 0;
  flex-shrink: 0;
}
/* Arrow now sits after read-time — push arrow to far right */
.page-module .th { justify-content: space-between; }
.page-module .th > span:first-child { flex: 1; }
body.light-mode .read-time {
  background: rgba(88,166,255,0.1);
  color: #5a6478;
}

/* ── Keyboard shortcut help overlay ────────────────────────── */
#shortcut-help {
  display: none;
  position: fixed;
  inset: 0;
  z-index: 8800;
  align-items: center;
  justify-content: center;
  background: rgba(0,0,0,0.55);
  backdrop-filter: blur(6px);
}
#shortcut-help.show { display: flex; }
.sh-card {
  background: var(--glass-bg);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  border: 1px solid rgba(88,166,255,0.2);
  border-radius: 18px;
  padding: 32px 36px;
  min-width: 280px;
  max-width: 360px;
  width: 90%;
  box-shadow: 0 20px 60px rgba(0,0,0,0.5);
  animation: card-in 0.3s var(--ease);
}
.sh-title {
  font-size: 1rem;
  font-weight: 700;
  color: var(--text);
  margin-bottom: 20px;
  text-align: center;
}
.sh-grid {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: 10px 16px;
  align-items: center;
  margin-bottom: 24px;
}
.sh-grid kbd {
  display: inline-block;
  padding: 3px 9px;
  background: rgba(88,166,255,0.1);
  border: 1px solid rgba(88,166,255,0.3);
  border-radius: 6px;
  font-family: var(--font-mono);
  font-size: 0.78rem;
  color: var(--blue);
  text-align: center;
  min-width: 36px;
  justify-self: start;
  white-space: nowrap;
}
.sh-grid span { font-size: 0.85rem; color: var(--muted); }
.sh-close {
  display: block;
  width: 100%;
  padding: 9px;
  border-radius: 10px;
  background: rgba(88,166,255,0.12);
  border: 1px solid rgba(88,166,255,0.25);
  color: var(--text);
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.2s;
  text-align: center;
}
.sh-close:hover {
  background: rgba(88,166,255,0.22);
  transform: translateY(-1px);
}

/* ── Shortcut hint button (⌨️ bottom-left) ─────────────────── */
#shortcut-hint-btn {
  position: fixed;
  bottom: 20px;
  left: 20px;
  z-index: 190;
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background: rgba(22,27,34,0.82);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid rgba(255,255,255,0.07);
  color: var(--muted);
  font-size: 1rem;
  cursor: pointer;
  box-shadow: 0 4px 16px rgba(0,0,0,0.35);
  transition: all 0.2s;
  display: flex;
  align-items: center;
  justify-content: center;
}
#shortcut-hint-btn:hover {
  color: var(--text);
  border-color: rgba(88,166,255,0.3);
  box-shadow: 0 6px 22px rgba(88,166,255,0.15);
  transform: translateY(-2px);
}
body.light-mode #shortcut-hint-btn {
  background: rgba(255,255,255,0.88);
  color: #5a6478;
}

/* ── Navigation toast ───────────────────────────────────────── */
#shortcut-toast {
  position: fixed;
  bottom: 70px;
  left: 50%;
  transform: translateX(-50%) translateY(10px);
  background: rgba(22,27,34,0.92);
  backdrop-filter: blur(12px);
  border: 1px solid rgba(255,255,255,0.08);
  border-radius: 10px;
  padding: 8px 20px;
  font-size: 0.82rem;
  color: var(--muted);
  z-index: 9000;
  opacity: 0;
  visibility: hidden;
  transition: all 0.25s var(--ease);
  white-space: nowrap;
  pointer-events: none;
}
#shortcut-toast.show {
  opacity: 1;
  visibility: visible;
  transform: translateX(-50%) translateY(0);
}

/* Mobile: hide shortcut hint btn and reading times on very small screens */
@media (max-width: 430px) {
  #shortcut-hint-btn { display: none; }
  .read-time { display: none; }
  #breadcrumb { font-size: 0.72rem; padding: 6px 10px; }
  #bc-topic { max-width: 160px; }
}