/* ============================================================
   CSA Compass — Design System
   Simple & flat: white + blue (light), black + blue (dark).
   No gradients, no glows, no glass. Clarity first.
   ============================================================ */

:root {
  --bg: #212121;
  --bg-soft: #282828;
  --bg-elevated: #2e2e2e;
  --surface: #282828;
  --surface-strong: #353535;
  --border: #3d3d3d;
  --border-strong: #4d4d4d;
  --text: #f5f5f5;
  --text-dim: #b0b0b0;
  --text-faint: #888888;
  --accent: #3b82f6;
  --accent-strong: #2563eb;
  --accent-soft: rgba(59, 130, 246, 0.14);
  --success: #22c55e;
  --success-strong: #16a34a;
  --success-soft: rgba(34, 197, 94, 0.14);
  --dot: rgba(255, 255, 255, 0.06);
  --danger: #f16161;
  --danger-strong: #dc2626;
  --danger-soft: rgba(239, 68, 68, 0.14);
  --warning: #eab308;
  --code-bg: #262626;
  --code-text: #e5e5e5;
  --radius: 10px;
  --radius-sm: 8px;
  --shadow: 0 1px 3px rgba(0, 0, 0, 0.3);
  --font: "Poppins", "Inter", -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --sb-w: 250px;
  --sb-w-min: 72px;
  --mono: "JetBrains Mono", "SF Mono", "Fira Code", Menlo, Consolas, monospace;
}

[data-theme="light"] {
  --bg: #f6f6f8;
  --bg-soft: #eeeef0;
  --bg-elevated: #ffffff;
  --surface: #ffffff;
  --surface-strong: #ececee;
  --border: #dddde1;
  --border-strong: #c7c7cc;
  --text: #0f172a;
  --text-dim: #475569;
  --text-faint: #5b6b7f;
  --accent: #2563eb;
  --accent-strong: #1d4ed8;
  --accent-soft: rgba(37, 99, 235, 0.08);
  --code-bg: #f1f5f9;
  --code-text: #0f172a;
  --shadow: 0 1px 3px rgba(15, 23, 42, 0.08);
  --dot: rgba(15, 23, 42, 0.07);
}

* { margin: 0; padding: 0; box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  font-family: var(--font);
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
  min-height: 100vh;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
  transition: background 0.2s ease, color 0.2s ease;
}

/* Decorative background removed — keep the page clean */
.bg-orbs { display: none; }

::selection { background: var(--accent-soft); }

a { color: inherit; text-decoration: none; }
img { max-width: 100%; }
button { font-family: inherit; cursor: pointer; }

.container { width: min(1120px, 92%); margin: 0 auto; }

/* ============ Card (formerly glass) ============ */
.glass {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  transition: border-color 0.2s ease;
}
.glass.hoverable:hover {
  background: var(--surface-strong);
}

/* ============ Buttons ============ */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 11px 22px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  font-size: 0.95rem;
  font-weight: 600;
  transition: background 0.2s ease, border-color 0.2s ease, color 0.2s ease;
}
.btn:active { transform: scale(0.98); }
.btn-primary {
  background: var(--accent);
  color: #fff;
}
.btn-primary:hover { background: var(--accent-strong); }
.btn-ghost {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border-strong);
}
.btn-ghost:hover { border-color: var(--accent); color: var(--accent); }
.btn-danger {
  background: transparent;
  color: var(--danger);
  border: 1px solid var(--danger);
}
.btn-danger:hover { background: var(--danger-soft); }
.btn-discord {
  background: #5865f2;
  color: #fff;
}
.btn-discord:hover { background: #4752c4; }
.btn-google {
  background: #fff;
  color: #1f1f1f;
  border: 1px solid #dadce0;
}
.btn-google:hover { background: #f8f9fa; }
.btn-google .ico { width: 18px; height: 18px; }
.btn-danger-solid {
  background: var(--danger);
  color: #fff;
}
.btn-danger-solid:hover { background: var(--danger-strong); }
.btn-sm { padding: 8px 16px; font-size: 0.85rem; }
.btn-block { width: 100%; }
.btn[disabled] { opacity: 0.5; cursor: not-allowed; transform: none !important; }

/* ============ Navbar ============ */
.navbar {
  position: sticky;
  top: 0;
  z-index: 100;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}
.nav-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 14px 0;
}
.brand { display: flex; align-items: center; gap: 12px; font-weight: 800; font-size: 1.15rem; }
.brand .logo-img {
  width: 38px;
  height: 38px;
  border-radius: 50%;
  object-fit: cover;
  border: 1px solid var(--border);
}
.brand span em { font-style: normal; color: var(--accent); }
.nav-links { display: flex; align-items: center; gap: 22px; }
.nav-links a:not(.btn) { color: var(--text-dim); font-weight: 500; font-size: 0.93rem; transition: color 0.2s; }
.nav-links a:not(.btn):hover { color: var(--text); }

.icon-btn {
  width: 38px; height: 38px;
  display: inline-flex; align-items: center; justify-content: center;
  border-radius: var(--radius-sm);
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
  font-size: 1rem;
  transition: background 0.2s, border-color 0.2s;
}
.icon-btn:hover { background: var(--surface-strong); }

/* Hamburger */
.hamburger {
  display: none;
  flex-direction: column;
  gap: 5px;
  background: none;
  border: none;
  padding: 8px;
}
.hamburger span {
  width: 24px; height: 2px;
  background: var(--text);
  border-radius: 2px;
  transition: transform 0.3s ease, opacity 0.3s ease;
}
.hamburger.open span:nth-child(1) { transform: translateY(7px) rotate(45deg); }
.hamburger.open span:nth-child(2) { opacity: 0; }
.hamburger.open span:nth-child(3) { transform: translateY(-7px) rotate(-45deg); }

.mobile-menu {
  display: none;
  flex-direction: column;
  gap: 6px;
  padding: 12px 4%;
  border-bottom: 1px solid var(--border);
  background: var(--bg);
}
.mobile-menu a {
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  color: var(--text-dim);
  font-weight: 500;
}
.mobile-menu a:hover { background: var(--surface-strong); color: var(--text); }
.mobile-menu.open { display: flex; }

/* ============ Hero (landing) ============ */
.hero {
  padding: 96px 0 72px;
  text-align: center;
}
.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  border-radius: 999px;
  background: var(--accent-soft);
  border: 1px solid var(--accent);
  color: var(--accent);
  font-size: 0.83rem;
  font-weight: 600;
  margin-bottom: 26px;
}
.hero h1 {
  font-size: clamp(2.4rem, 6vw, 4rem);
  font-weight: 800;
  line-height: 1.12;
  letter-spacing: -0.02em;
  margin-bottom: 20px;
}
.hero h1 .grad { color: var(--accent); }
.hero p.sub {
  max-width: 640px;
  margin: 0 auto 36px;
  color: var(--text-dim);
  font-size: 1.13rem;
}
.hero-cta { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.hero-logo {
  width: 88px; height: 88px;
  border-radius: 50%;
  object-fit: cover;
  margin: 0 auto 28px;
  display: block;
  border: 1px solid var(--border);
}

.stats-row {
  display: flex;
  justify-content: center;
  gap: 14px;
  flex-wrap: wrap;
  margin-top: 52px;
}
.stat-chip {
  padding: 16px 28px;
  text-align: center;
  min-width: 150px;
}
.stat-chip .num {
  font-size: 1.7rem;
  font-weight: 800;
  color: var(--accent);
}
.stat-chip .lbl { color: var(--text-dim); font-size: 0.85rem; }

/* ============ Sections ============ */
.section { padding: 72px 0; }
.section-head { text-align: center; margin-bottom: 44px; }
.section-head h2 { font-size: clamp(1.7rem, 4vw, 2.4rem); font-weight: 800; letter-spacing: -0.015em; margin-bottom: 10px; }
.section-head p { color: var(--text-dim); max-width: 560px; margin: 0 auto; }

.grid-3 { display: grid; grid-template-columns: repeat(3, 1fr); gap: 20px; }
.grid-2 { display: grid; grid-template-columns: repeat(2, 1fr); gap: 20px; }

.feature-card { padding: 28px; }
.feature-card .icon {
  width: 48px; height: 48px;
  border-radius: var(--radius-sm);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.4rem;
  background: var(--accent-soft);
  margin-bottom: 18px;
}
.feature-card h3 { font-size: 1.1rem; margin-bottom: 8px; }
.feature-card p { color: var(--text-dim); font-size: 0.93rem; }

/* Curriculum preview on landing */
.phase-row {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 18px 24px;
  margin-bottom: 12px;
}
.phase-row .phase-num {
  min-width: 44px; height: 44px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700;
  background: var(--accent);
  color: #fff;
  font-size: 0.95rem;
}
.phase-row .info { flex: 1; }
.phase-row .info h4 { font-size: 1.02rem; }
.phase-row .info p { color: var(--text-dim); font-size: 0.87rem; }
.phase-row .count { color: var(--text-faint); font-size: 0.83rem; white-space: nowrap; }

/* Discord section */
.discord-card {
  padding: 52px 36px;
  text-align: center;
}
.discord-card h2 { font-size: 1.8rem; margin-bottom: 12px; }
.discord-card p { color: var(--text-dim); margin-bottom: 26px; max-width: 480px; margin-inline: auto; }

/* Footer */
.footer {
  border-top: 1px solid var(--border);
  padding: 36px 0;
  margin-top: 40px;
}
.footer-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  flex-wrap: wrap;
}
.footer p { color: var(--text-faint); font-size: 0.88rem; }
.footer-links { display: flex; gap: 18px; align-items: center; }
.footer-links a { color: var(--text-dim); font-size: 0.88rem; transition: color 0.2s; }
.footer-links a:hover { color: var(--text); }

/* ============ Auth (login) ============ */
.auth-wrap {
  min-height: calc(100vh - 76px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 40px 4%;
}
.auth-card {
  width: min(420px, 100%);
  padding: 42px 36px;
  text-align: center;
}
.auth-card .hero-logo { width: 64px; height: 64px; margin-bottom: 20px; }
.auth-card h1 { font-size: 1.6rem; margin-bottom: 6px; }
.auth-card > p { color: var(--text-dim); font-size: 0.93rem; margin-bottom: 28px; }
.field { text-align: left; margin-bottom: 18px; }
.field label { display: block; font-size: 0.85rem; font-weight: 600; color: var(--text-dim); margin-bottom: 7px; }
.field input {
  width: 100%;
  padding: 12px 14px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
  background: var(--bg);
  color: var(--text);
  font-size: 0.95rem;
  font-family: inherit;
  transition: border-color 0.2s, box-shadow 0.2s;
}
.field input:focus {
  outline: none;
  border-color: var(--accent);
  box-shadow: 0 0 0 3px var(--accent-soft);
}
.auth-divider {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 18px 0;
  color: var(--text-faint);
  font-size: 0.8rem;
}
.auth-divider::before,
.auth-divider::after {
  content: "";
  flex: 1;
  height: 1px;
  background: var(--border);
}
.auth-error {
  display: none;
  background: var(--danger-soft);
  border: 1px solid var(--danger);
  color: var(--danger);
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  margin-bottom: 16px;
}
.auth-error.show { display: block; }
.auth-note { margin-top: 20px; color: var(--text-faint); font-size: 0.8rem; }

/* ============ Profile page ============ */
.profile-card {
  display: flex;
  align-items: center;
  gap: 20px;
  padding: 24px;
  margin-bottom: 22px;
}
.profile-avatar {
  width: 72px;
  height: 72px;
  flex-shrink: 0;
  border-radius: 50%;
  background: var(--accent-soft);
  color: var(--accent);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  font-weight: 700;
  overflow: hidden;
}
.profile-avatar img { width: 100%; height: 100%; object-fit: cover; }
.profile-info { min-width: 0; }
.profile-name { font-size: 1.25rem; font-weight: 700; }
.profile-email { color: var(--text-dim); font-size: 0.92rem; margin-top: 2px; word-break: break-all; }
.profile-badge {
  display: inline-block;
  margin-top: 8px;
  padding: 3px 10px;
  border-radius: 999px;
  background: var(--surface-strong);
  border: 1px solid var(--border);
  color: var(--text-dim);
  font-size: 0.75rem;
  font-weight: 600;
}

/* ============ Dashboard ============ */
.dash-header { padding: 44px 0 10px; }
.dash-header h1 { font-size: clamp(1.6rem, 4vw, 2.2rem); font-weight: 800; }
.dash-header p { color: var(--text-dim); margin-top: 4px; }

.progress-overview {
  padding: 26px 28px;
  margin: 26px 0 34px;
}
.progress-overview .row {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  margin-bottom: 12px;
  flex-wrap: wrap;
  gap: 8px;
}
.progress-overview h2 { font-size: 1.05rem; font-weight: 700; }
.progress-overview .pct { font-weight: 800; font-size: 1.3rem; color: var(--accent); }

.progress-bar {
  height: 8px;
  border-radius: 999px;
  background: var(--surface-strong);
  border: 1px solid var(--border);
  overflow: hidden;
}
.progress-bar .fill {
  height: 100%;
  border-radius: 999px;
  background: var(--accent);
  transition: width 0.5s ease;
}
.progress-bar.thin { height: 6px; }
.progress-meta { color: var(--text-faint); font-size: 0.83rem; margin-top: 10px; }

/* Unit accordion */
.unit-card { margin-bottom: 16px; overflow: hidden; }
.unit-head {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 20px 24px;
  cursor: pointer;
  user-select: none;
  transition: background 0.2s;
}
.unit-head:hover { background: var(--surface-strong); }
.unit-head .phase-num {
  min-width: 44px; height: 44px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-weight: 700;
  font-size: 0.95rem;
  background: var(--accent);
  color: #fff;
}
.unit-card.unit-done .phase-num { background: var(--success); }
.unit-head .info { flex: 1; min-width: 0; }
.unit-head .info h3 { font-size: 1.05rem; }
.unit-head .info .progress-bar { margin-top: 9px; max-width: 320px; }
.unit-head .meta { color: var(--text-faint); font-size: 0.82rem; white-space: nowrap; }
.unit-head .chev { color: var(--text-faint); transition: transform 0.3s ease; font-size: 0.8rem; }
.unit-card.expanded .chev { transform: rotate(180deg); }

.unit-lessons {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.4s ease;
}
.unit-card.expanded .unit-lessons { max-height: 1800px; }
.unit-lessons-inner { padding: 4px 24px 20px; display: flex; flex-direction: column; gap: 8px; }

.lesson-row {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 13px 16px;
  border-radius: var(--radius-sm);
  border: 1px solid transparent;
  transition: background 0.2s, border-color 0.2s;
}
.lesson-row.unlocked { cursor: pointer; }
.lesson-row.unlocked:hover { background: var(--surface-strong); border-color: var(--border); }
.lesson-row .status {
  min-width: 30px; height: 30px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  font-size: 0.8rem;
  border: 1.5px solid var(--border-strong);
  color: var(--text-faint);
  font-weight: 700;
}
.lesson-row.done .status {
  background: var(--success);
  border-color: var(--success);
  color: #fff;
}
.lesson-row.current .status {
  border-color: var(--accent);
  color: var(--accent);
}
.lesson-row .l-title { flex: 1; font-size: 0.95rem; font-weight: 500; min-width: 0; }
.lesson-row .l-tag { font-size: 0.75rem; color: var(--text-faint); }
.lesson-row.done .l-title { color: var(--text-dim); }

/* unit-exam checkpoint at the bottom of a phase's lessons */
.unit-exam-row {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 13px 16px;
  margin-top: 2px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface);
  cursor: pointer;
  text-decoration: none;
  transition: background 0.2s, border-color 0.2s;
}
.unit-exam-row:hover { background: var(--surface-strong); }
.unit-exam-row .status {
  min-width: 30px; height: 30px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  border: 1.5px solid var(--accent);
  color: var(--accent);
}
.unit-exam-row .l-title { flex: 1; font-size: 0.95rem; font-weight: 600; color: var(--text); }
.unit-exam-row .l-tag { font-size: 0.75rem; color: var(--accent); font-weight: 600; }

/* ============ Lesson page ============ */
.lesson-wrap { padding: 36px 0 80px; }
.lesson-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 26px;
  flex-wrap: wrap;
}
.lesson-topbar .back-link {
  color: var(--text-dim);
  font-size: 0.9rem;
  font-weight: 500;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  transition: color 0.2s;
}
.lesson-topbar .back-link:hover { color: var(--text); }
.lesson-unit-tag {
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 5px 14px;
  border-radius: 999px;
}

.lesson-header h1 { font-size: clamp(1.5rem, 4vw, 2.1rem); font-weight: 800; margin-bottom: 8px; }
.lesson-header .objective { color: var(--text-dim); font-size: 1rem; margin-bottom: 28px; }

.lesson-section { margin-bottom: 30px; padding: 30px; }
.lesson-section .sec-label {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
  margin-bottom: 18px;
}

/* Video */
.video-frame {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 9;
  border-radius: var(--radius-sm);
  overflow: hidden;
  background: var(--surface-strong);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  gap: 12px;
}
.video-frame iframe { position: absolute; inset: 0; width: 100%; height: 100%; border: 0; }
.video-frame .play-circle {
  width: 70px; height: 70px;
  border-radius: 50%;
  background: var(--accent);
  display: flex; align-items: center; justify-content: center;
  font-size: 1.5rem;
  color: #fff;
}
.video-frame .vf-note { color: var(--text-dim); font-size: 0.9rem; }
.bonus-video {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin-top: 14px;
  font-size: 0.88rem;
  font-weight: 600;
  color: var(--accent);
}
.bonus-video:hover { text-decoration: underline; }
.bonus-video .ico { width: 15px; height: 15px; }

/* Reading typography */
.reading h3 { font-size: 1.2rem; margin: 26px 0 10px; font-weight: 700; }
.reading h3:first-child { margin-top: 0; }
.reading p { color: var(--text-dim); margin-bottom: 14px; font-size: 0.97rem; }
.reading strong { color: var(--text); }
.reading ul, .reading ol { margin: 0 0 16px 22px; color: var(--text-dim); font-size: 0.95rem; }
.reading li { margin-bottom: 6px; }
/* Keep >=, <=, !=, ->, == as literal two-character shapes — disable the
   programming ligatures JetBrains Mono / Cascadia Code turn on by default
   (this matches VS Code's own default, editor.fontLigatures: false). */
code, pre, kbd, samp {
  font-variant-ligatures: none;
  font-feature-settings: "liga" 0, "clig" 0, "calt" 0, "dlig" 0;
}

.reading code {
  font-family: var(--mono);
  font-size: 0.85em;
  background: var(--code-bg);
  border: 1px solid var(--border);
  padding: 2px 7px;
  border-radius: 6px;
  color: var(--accent);
}
.reading pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 18px 20px;
  overflow-x: auto;
  margin: 6px 0 18px;
}
.reading pre code {
  background: none;
  border: none;
  padding: 0;
  color: var(--code-text);
  font-size: 0.86rem;
  line-height: 1.65;
}
.callout {
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  padding: 14px 18px;
  margin: 6px 0 18px;
  font-size: 0.92rem;
  color: var(--text-dim);
}
.callout strong { color: var(--text); }

/* Practice */
.q-card {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 22px;
  margin-bottom: 18px;
  background: var(--surface);
  transition: border-color 0.3s;
}
.q-card.correct { border-color: var(--success); }
.q-card.incorrect { border-color: var(--danger); }
.q-top { display: flex; gap: 12px; align-items: baseline; margin-bottom: 8px; }
.q-num {
  font-size: 0.75rem;
  font-weight: 800;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 3px 11px;
  border-radius: 999px;
  white-space: nowrap;
}
.q-type { font-size: 0.72rem; color: var(--text-faint); text-transform: uppercase; letter-spacing: 0.06em; font-weight: 700; }
.q-text { font-size: 0.98rem; font-weight: 500; margin-bottom: 14px; }
.q-text pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 14px 16px;
  overflow-x: auto;
  margin: 12px 0 4px;
  font-weight: 400;
}
.q-text pre code { font-family: var(--mono); font-size: 0.84rem; color: var(--code-text); line-height: 1.6; background: none; border: none; padding: 0; }
.q-text code { font-family: var(--mono); font-size: 0.85em; background: var(--code-bg); border: 1px solid var(--border); padding: 1px 6px; border-radius: 5px; color: var(--accent); }

/* ============================================================
   VS Code (Dark+) code blocks
   Every <pre><code> gets a .code-panel class from app.js and is
   painted to match VS Code's Dark+ editor. Always dark, regardless
   of the page's light/dark theme. Token colors come from the
   .tok-* spans the highlighter injects.
   ============================================================ */
pre.code-panel {
  position: relative;
  background: #1e1e1e;
  border: 1px solid #333333;
  border-radius: 8px;
  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.35);
  padding: 46px 20px 20px;
  margin: 10px 0 20px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}
/* title bar strip */
pre.code-panel::before {
  content: "";
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 34px;
  background: #252526;
  border-bottom: 1px solid #333333;
  border-radius: 8px 8px 0 0;
}
/* three window-control dots (red / yellow / green) */
pre.code-panel::after {
  content: "";
  position: absolute;
  top: 12px; left: 16px;
  width: 11px; height: 11px;
  border-radius: 50%;
  background: #ff5f56;
  box-shadow: 18px 0 0 #ffbd2e, 36px 0 0 #27c93f;
  z-index: 1;
}
pre.code-panel > code {
  display: block;
  background: none;
  border: none;
  padding: 0;
  color: #d4d4d4;
  font-family: "Cascadia Code", "Cascadia Mono", "Consolas", "SF Mono", Menlo, "JetBrains Mono", monospace;
  font-size: 14px;
  line-height: 1.6;
  white-space: pre;
  tab-size: 4;
  -moz-tab-size: 4;
}
/* Dark+ syntax token colors */
pre.code-panel .tok-keyword { color: #569CD6; }
pre.code-panel .tok-string  { color: #CE9178; }
pre.code-panel .tok-comment { color: #6A9955; }
pre.code-panel .tok-number  { color: #B5CEA8; }
pre.code-panel .tok-method  { color: #DCDCAA; }
pre.code-panel .tok-class   { color: #4EC9B0; }
/* dark scrollbar to match the panel */
pre.code-panel::-webkit-scrollbar { height: 10px; }
pre.code-panel::-webkit-scrollbar-track { background: transparent; }
pre.code-panel::-webkit-scrollbar-thumb { background: #424242; border-radius: 5px; border: 2px solid #1e1e1e; }
pre.code-panel::-webkit-scrollbar-thumb:hover { background: #4f4f4f; }

/* ---- Light mode: VS Code "Light+" palette (only when the site is light) ---- */
[data-theme="light"] pre.code-panel {
  background: #ffffff;
  border-color: #e3e3e3;
  box-shadow: 0 6px 20px rgba(15, 23, 42, 0.10);
}
[data-theme="light"] pre.code-panel::before {
  background: #f3f3f3;
  border-bottom-color: #e3e3e3;
}
/* window dots keep the universal red / yellow / green */
[data-theme="light"] pre.code-panel > code { color: #1f1f1f; }
[data-theme="light"] pre.code-panel .tok-keyword { color: #0000FF; }
[data-theme="light"] pre.code-panel .tok-string  { color: #A31515; }
[data-theme="light"] pre.code-panel .tok-comment { color: #008000; }
[data-theme="light"] pre.code-panel .tok-number  { color: #098658; }
[data-theme="light"] pre.code-panel .tok-method  { color: #795E26; }
[data-theme="light"] pre.code-panel .tok-class   { color: #267F99; }
[data-theme="light"] pre.code-panel::-webkit-scrollbar-thumb { background: #c1c1c1; border-color: #ffffff; }
[data-theme="light"] pre.code-panel::-webkit-scrollbar-thumb:hover { background: #a8a8a8; }

.q-options { display: flex; flex-direction: column; gap: 9px; }
.q-option {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border);
  background: var(--surface);
  cursor: pointer;
  transition: border-color 0.2s, background 0.2s;
  font-size: 0.92rem;
  text-align: left;
  color: var(--text);
  width: 100%;
}
.q-option:hover:not([disabled]) { background: var(--surface-strong); }
.q-option .opt-key {
  min-width: 26px; height: 26px;
  border-radius: 50%;
  border: 1.5px solid var(--border-strong);
  display: flex; align-items: center; justify-content: center;
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--text-dim);
  flex-shrink: 0;
}
.q-option.selected { border-color: var(--accent); background: var(--accent-soft); }
.q-option.right { border-color: var(--success); background: var(--success-soft); }
.q-option.right .opt-key { border-color: var(--success); color: var(--success); }
.q-option.wrong { border-color: var(--danger); background: var(--danger-soft); }
.q-option.wrong .opt-key { border-color: var(--danger); color: var(--danger); }
.q-option code { font-family: var(--mono); font-size: 0.85em; white-space: pre-wrap; }
/* Code answer choices are shown multi-line (like the AP exam) and stay
   monochrome — the syntax highlighter only touches <pre><code>, not the
   inline <code> used here, so options never get color. */
.q-option:has(code) { align-items: flex-start; }
.q-option:has(code) .opt-key { margin-top: 1px; }
.q-option:has(code) > span:last-child { display: block; line-height: 1.55; }
.q-option[disabled] { cursor: default; }

.q-input {
  width: 100%;
  padding: 12px 16px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
  background: var(--bg);
  color: var(--text);
  font-family: var(--mono);
  font-size: 0.9rem;
  transition: border-color 0.2s, box-shadow 0.2s;
}
.q-input:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }
textarea.q-input { min-height: 120px; resize: vertical; line-height: 1.6; }

.q-actions { display: flex; gap: 10px; margin-top: 14px; flex-wrap: wrap; }

.feedback {
  margin-top: 14px;
  padding: 14px 18px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  display: none;
}
.feedback.show { display: block; }
.feedback.good { background: var(--success-soft); border: 1px solid var(--success); color: var(--success); }
.feedback.bad { background: var(--danger-soft); border: 1px solid var(--danger); color: var(--danger); }
.feedback .expl { color: var(--text-dim); margin-top: 6px; display: block; }
.feedback .expl code { font-family: var(--mono); font-size: 0.85em; }

/* Lesson progress + completion */
.lesson-progress-sticky {
  position: sticky;
  top: 76px;
  z-index: 50;
  padding: 12px 20px;
  margin-bottom: 24px;
  display: flex;
  align-items: center;
  gap: 16px;
  background: var(--bg);
}
.lesson-progress-sticky .progress-bar { flex: 1; }
.lesson-progress-sticky .lbl { font-size: 0.82rem; color: var(--text-dim); white-space: nowrap; font-weight: 600; }

.completion-panel {
  text-align: center;
  padding: 48px 32px;
  display: none;
}
.completion-panel.show { display: block; }
.completion-panel .big-check {
  width: 80px; height: 80px;
  margin: 0 auto 20px;
  border-radius: 50%;
  background: var(--success);
  display: flex; align-items: center; justify-content: center;
  font-size: 2.2rem;
  color: #fff;
}
.completion-panel h2 { font-size: 1.6rem; margin-bottom: 8px; }
.completion-panel p { color: var(--text-dim); margin-bottom: 26px; }
.completion-panel .cta-row { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

/* ============ Modal (settings) ============ */
.modal-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  z-index: 200;
  display: none;
  align-items: center;
  justify-content: center;
  padding: 20px;
}
.modal-overlay.open { display: flex; }
.modal {
  width: min(440px, 100%);
  padding: 30px;
  background: var(--bg-elevated);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  position: relative;
}
.modal h2 { font-size: 1.3rem; margin-bottom: 4px; }
.modal .modal-sub { color: var(--text-dim); font-size: 0.88rem; margin-bottom: 24px; }
.modal-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 15px 0;
  border-top: 1px solid var(--border);
}
.modal-row .lbl { font-weight: 600; font-size: 0.93rem; }
.modal-row .desc { color: var(--text-faint); font-size: 0.8rem; }
.modal-close {
  position: absolute;
  top: 18px; right: 18px;
}
.confirm-modal .modal-sub { margin-bottom: 24px; }
.confirm-actions {
  display: flex;
  gap: 12px;
  justify-content: flex-end;
  flex-wrap: wrap;
}
.confirm-actions .btn { flex: 0 1 auto; }

/* Toggle switch */
.switch { position: relative; width: 48px; height: 26px; flex-shrink: 0; }
.switch input { opacity: 0; width: 0; height: 0; }
.switch .slider {
  position: absolute;
  inset: 0;
  border-radius: 999px;
  background: var(--surface-strong);
  border: 1px solid var(--border-strong);
  transition: background 0.2s, border-color 0.2s;
  cursor: pointer;
}
.switch .slider::before {
  content: "";
  position: absolute;
  width: 18px; height: 18px;
  left: 3px; top: 3px;
  border-radius: 50%;
  background: var(--text-dim);
  transition: transform 0.2s ease, background 0.2s;
}
.switch input:checked + .slider { background: var(--accent); border-color: var(--accent); }
.switch input:checked + .slider::before { transform: translateX(22px); background: #fff; }

/* Toast */
.toast {
  position: fixed;
  bottom: 28px;
  left: 50%;
  transform: translateX(-50%) translateY(80px);
  background: var(--bg-elevated);
  border: 1px solid var(--border-strong);
  color: var(--text);
  padding: 12px 24px;
  border-radius: var(--radius-sm);
  font-size: 0.9rem;
  font-weight: 500;
  box-shadow: var(--shadow);
  z-index: 300;
  opacity: 0;
  transition: transform 0.3s ease, opacity 0.3s;
  pointer-events: none;
  max-width: 92%;
  text-align: center;
}
.toast.show { transform: translateX(-50%) translateY(0); opacity: 1; }

/* Reveal on scroll — content is always visible; no animation */
.reveal { opacity: 1; transform: none; }
.reveal.visible { opacity: 1; transform: none; }

/* ============ Inline SVG icons ============ */
.ico { width: 1.1em; height: 1.1em; flex-shrink: 0; display: inline-block; vertical-align: -0.18em; }
.icon-btn .ico { width: 17px; height: 17px; vertical-align: 0; }
.feature-card .icon .ico { width: 22px; height: 22px; color: var(--accent); }
.hero-badge .ico { width: 15px; height: 15px; margin-right: 7px; }
.sec-label .ico { width: 15px; height: 15px; }
.unit-head .info h3 { display: flex; align-items: center; gap: 8px; }
.unit-head .info h3 .ico { width: 17px; height: 17px; color: var(--accent); }
.phase-num .ico { width: 18px; height: 18px; }
.lesson-row .status .ico { width: 13px; height: 13px; }
.chev .ico { width: 15px; height: 15px; }
.big-check .ico { width: 38px; height: 38px; }
.play-circle .ico { width: 26px; height: 26px; }
.lesson-unit-tag { display: inline-flex; align-items: center; gap: 6px; }
.lesson-unit-tag .ico { width: 13px; height: 13px; }
.feedback .ico { width: 14px; height: 14px; }
.lesson-progress-sticky .lbl { display: inline-flex; align-items: center; gap: 6px; }
.lesson-progress-sticky .lbl .ico { width: 14px; height: 14px; color: var(--accent); }
.btn .ico { width: 15px; height: 15px; }

/* ============ AI tutor ============ */
.ask-ai-lesson { margin-bottom: 26px; display: inline-flex; gap: 8px; }
.ask-ai-lesson .ico { color: var(--accent); }
.q-top .tutor-open {
  margin-left: auto;
  display: inline-flex; align-items: center; gap: 6px;
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-dim);
  font-size: 0.78rem; font-weight: 600;
  padding: 5px 12px; border-radius: 999px;
  transition: background 0.2s, border-color 0.2s, color 0.2s;
}
.q-top .tutor-open:hover { background: var(--surface-strong); color: var(--text); }
.tutor-open .ico { width: 13px; height: 13px; }

.tutor-drawer {
  position: fixed; top: 0; right: 0; height: 100dvh;
  width: min(420px, 100vw);
  background: var(--bg);
  border-left: 1px solid var(--border);
  z-index: 250;
  display: flex; flex-direction: column;
  transform: translateX(100%);
  transition: transform 0.25s ease;
}
.tutor-drawer.open { transform: translateX(0); }
.tutor-head {
  display: flex; align-items: center; justify-content: space-between;
  gap: 10px; padding: 14px 18px;
  border-bottom: 1px solid var(--border);
}
.tutor-title { display: inline-flex; align-items: center; gap: 8px; font-weight: 700; }
.tutor-title .ico { width: 16px; height: 16px; color: var(--accent); }
.tutor-ctx { padding: 9px 18px; font-size: 0.8rem; font-weight: 600; color: var(--accent); background: var(--accent-soft); }
.tutor-msgs { flex: 1; overflow-y: auto; padding: 18px; display: flex; flex-direction: column; gap: 10px; }
.tutor-empty { text-align: center; color: var(--text-dim); font-size: 0.9rem; padding: 28px 12px; }
.tutor-empty .ico { width: 26px; height: 26px; color: var(--accent); display: block; margin: 0 auto 10px; }
.t-msg { max-width: 88%; padding: 10px 14px; border-radius: var(--radius-sm); font-size: 0.9rem; line-height: 1.55; }
.t-msg.student { align-self: flex-end; background: var(--accent); color: #fff; }
.t-msg.tutor { align-self: flex-start; background: var(--surface-strong); border: 1px solid var(--border); }
.t-msg.err { border-color: var(--danger); color: var(--danger); background: var(--danger-soft); }
.t-msg code { font-family: var(--mono); font-size: 0.85em; background: var(--code-bg); border: 1px solid var(--border); border-radius: 5px; padding: 1px 5px; }
.t-msg.student code { background: rgba(255, 255, 255, 0.18); border-color: transparent; color: #fff; }
.t-msg.typing { display: flex; gap: 5px; padding: 14px; }
.t-msg.typing span { width: 7px; height: 7px; border-radius: 50%; background: var(--text-faint); animation: blink 1.2s infinite; }
.t-msg.typing span:nth-child(2) { animation-delay: 0.2s; }
.t-msg.typing span:nth-child(3) { animation-delay: 0.4s; }
@keyframes blink { 0%, 80%, 100% { opacity: 0.25; } 40% { opacity: 1; } }
.tutor-suggests { display: flex; flex-wrap: wrap; gap: 8px; padding: 0 18px 12px; }
.tutor-suggest {
  border: 1px solid var(--border-strong);
  background: transparent;
  color: var(--text-dim);
  border-radius: 999px;
  padding: 7px 14px;
  font-size: 0.8rem; font-weight: 500;
  transition: background 0.2s, border-color 0.2s, color 0.2s;
}
.tutor-suggest:hover { background: var(--surface-strong); color: var(--text); }
.tutor-inputrow {
  display: flex; gap: 10px; align-items: flex-end;
  padding: 12px 18px 16px;
  border-top: 1px solid var(--border);
}
.tutor-inputrow textarea {
  flex: 1; resize: none;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-strong);
  background: var(--bg);
  color: var(--text);
  font-family: inherit;
  font-size: 0.9rem;
  line-height: 1.5;
}
.tutor-inputrow textarea:focus { outline: none; border-color: var(--accent); box-shadow: 0 0 0 3px var(--accent-soft); }

/* ============ Responsive ============ */
@media (max-width: 900px) {
  .grid-3 { grid-template-columns: repeat(2, 1fr); }
}
@media (max-width: 720px) {
  .nav-links { display: none; }
  .hamburger { display: flex; }
  .grid-3, .grid-2 { grid-template-columns: 1fr; }
  .hero { padding: 64px 0 48px; }
  .section { padding: 52px 0; }
  .lesson-section { padding: 22px 18px; }
  .unit-head { padding: 16px 16px; gap: 12px; }
  .unit-lessons-inner { padding: 4px 12px 16px; }
  .unit-head .meta { display: none; }
  .auth-card { padding: 32px 22px; }
  .lesson-progress-sticky { top: 70px; }
  .phase-row { padding: 14px 16px; }
  .lesson-row .l-tag { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; transition-duration: 0.01ms !important; }
}

/* ============================================================
   Left sidebar (app pages: dashboard, lesson, tests)
   Expandable/retractable; state persisted in localStorage.
   ============================================================ */
body.has-sb { padding-left: var(--sb-w); transition: padding-left 0.22s ease; }
html.sb-collapsed body.has-sb { padding-left: var(--sb-w-min); }

.sidebar {
  position: fixed;
  top: 0; left: 0; bottom: 0;
  width: var(--sb-w);
  background: var(--bg);
  border-right: 1px solid var(--border);
  display: flex;
  flex-direction: column;
  z-index: 150;
  transition: width 0.22s ease, transform 0.22s ease;
  overflow: hidden;
}
html.sb-collapsed .sidebar { width: var(--sb-w-min); }

.sb-head {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 13px 12px;
  border-bottom: 1px solid var(--border);
  min-height: 65px;
}
.sb-head .brand { min-width: 0; overflow: hidden; }
.sb-head .brand .logo-img { width: 34px; height: 34px; flex-shrink: 0; }
.sb-head .brand span { white-space: nowrap; font-size: 1.02rem; }
.sb-toggle { margin-left: auto; flex-shrink: 0; border: none; }
html.sb-collapsed .sb-head { justify-content: center; padding: 13px 8px; }
html.sb-collapsed .sb-head .brand { display: none; }
html.sb-collapsed .sb-toggle { margin-left: 0; }

.sb-nav { flex: 1; padding: 12px 10px; display: flex; flex-direction: column; gap: 4px; overflow-y: auto; }
.sb-foot { padding: 12px 10px; border-top: 1px solid var(--border); display: flex; flex-direction: column; gap: 4px; }

.sb-link {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  border: none;
  background: transparent;
  color: var(--text-dim);
  font-weight: 500;
  font-size: 0.92rem;
  font-family: inherit;
  width: 100%;
  text-align: left;
  white-space: nowrap;
  transition: background 0.15s, color 0.15s;
}
.sb-link:hover { background: var(--surface-strong); color: var(--text); }
.sb-link.active { background: var(--accent-soft); color: var(--accent); font-weight: 600; }
.sb-link .ico { width: 18px; height: 18px; flex-shrink: 0; }
.sb-link [data-theme-icon] { display: inline-flex; }
.sb-link [data-theme-icon] .ico { width: 18px; height: 18px; }
html.sb-collapsed .sb-link { justify-content: center; padding: 10px 0; }
html.sb-collapsed .sb-txt { display: none; }

/* Discord + Log out get their own solid-color buttons, not plain nav rows */
.sb-link.sb-btn { margin-top: 6px; font-weight: 700; }
.sb-btn-discord { background: #5865f2; color: #fff; }
.sb-btn-discord:hover { background: #4752c4; color: #fff; }
.sb-btn-discord .ico-discord { width: 17px; height: 17px; }
.sb-btn-danger { background: var(--danger); color: #fff; }
.sb-btn-danger:hover { background: var(--danger-strong); color: #fff; }

/* Mobile topbar + off-canvas drawer */
.mobile-topbar {
  display: none;
  position: sticky;
  top: 0;
  z-index: 120;
  align-items: center;
  gap: 12px;
  padding: 10px 4%;
  background: var(--bg);
  border-bottom: 1px solid var(--border);
}
.mobile-topbar .brand .logo-img { width: 32px; height: 32px; }
.sb-backdrop {
  display: none;
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.55);
  z-index: 149;
}

/* Lesson sticky bar sits under no top navbar on sidebar pages */
body.has-sb .lesson-progress-sticky { top: 12px; }

@media (max-width: 860px) {
  body.has-sb { padding-left: 0 !important; }
  .sidebar { transform: translateX(-101%); width: var(--sb-w) !important; box-shadow: 4px 0 24px rgba(0,0,0,0.25); }
  html.sb-open .sidebar { transform: translateX(0); }
  html.sb-open .sb-backdrop { display: block; }
  html.sb-collapsed .sb-head .brand { display: flex; }   /* drawer always full-width */
  html.sb-collapsed .sb-txt { display: inline; }
  html.sb-collapsed .sb-link { justify-content: flex-start; padding: 10px 12px; }
  .sb-toggle { display: none; }
  .mobile-topbar { display: flex; }
  body.has-sb .lesson-progress-sticky { top: 62px; }
}

/* ============================================================
   Practice tests
   ============================================================ */
.tests-wrap { padding-bottom: 80px; }
.tests-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(300px, 1fr));
  gap: 20px;
  margin-top: 18px;
}
.tests-section-head { margin-top: 34px; }
.tests-section-head:first-child { margin-top: 26px; }
.tests-section-head h2 { font-size: 1.15rem; display: flex; align-items: center; gap: 8px; }
.tests-section-head p { color: var(--text-dim); font-size: 0.88rem; margin-top: 4px; }
.test-card.unit h3 .ico { color: var(--accent); }
.test-card { padding: 24px; display: flex; flex-direction: column; gap: 10px; }
.test-card .t-num {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--accent);
}
.test-card h3 { font-size: 1.08rem; display: flex; align-items: center; gap: 9px; }
.test-card h3 .ico { width: 17px; height: 17px; color: var(--accent); }
.test-card .t-desc { color: var(--text-dim); font-size: 0.88rem; flex: 1; }
.test-card .t-meta { display: flex; gap: 14px; color: var(--text-faint); font-size: 0.8rem; flex-wrap: wrap; }
.test-card .t-meta span { display: inline-flex; align-items: center; gap: 5px; }
.test-card .t-meta .ico { width: 13px; height: 13px; }
.test-card .t-best { font-size: 0.82rem; font-weight: 700; }
.test-card .t-best.good { color: var(--success); }
.test-card .t-best.none { color: var(--text-faint); font-weight: 500; }

.test-sticky {
  position: sticky;
  top: 12px;
  z-index: 50;
  padding: 12px 20px;
  margin-bottom: 24px;
  display: flex;
  align-items: center;
  gap: 16px;
  background: var(--bg);
}
.test-sticky .progress-bar { flex: 1; }
.test-sticky .lbl { font-size: 0.82rem; color: var(--text-dim); white-space: nowrap; font-weight: 600; }
.test-sticky .timer {
  font-family: var(--mono);
  font-size: 0.92rem;
  font-weight: 600;
  color: var(--text);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.test-sticky .timer .ico { width: 14px; height: 14px; color: var(--accent); }
.test-sticky .timer.low { color: var(--danger); }
.test-sticky .timer.low .ico { color: var(--danger); }

.result-panel {
  text-align: center;
  padding: 40px 28px;
  margin-bottom: 26px;
}
.result-panel .r-score {
  font-size: 3rem;
  font-weight: 800;
  color: var(--accent);
  line-height: 1.1;
}
.result-panel .r-score.good { color: var(--success); }
.result-panel .r-score.bad { color: var(--danger); }
.result-panel .r-sub { color: var(--text-dim); margin: 6px 0 4px; font-weight: 600; }
.result-panel .r-best { color: var(--text-faint); font-size: 0.85rem; margin-bottom: 22px; }
.result-panel .cta-row { display: flex; gap: 12px; justify-content: center; flex-wrap: wrap; }

@media (max-width: 720px) {
  .test-sticky { flex-wrap: wrap; gap: 10px; }
  .test-sticky .progress-bar { flex-basis: 100%; order: 3; }
}

/* Dashboard promo row for tests */
.tests-promo {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 20px 24px;
  margin-bottom: 34px;
}
.tests-promo .tp-ico {
  width: 44px; height: 44px;
  border-radius: var(--radius-sm);
  background: var(--accent-soft);
  display: flex; align-items: center; justify-content: center;
  flex-shrink: 0;
}
.tests-promo .tp-ico .ico { width: 20px; height: 20px; color: var(--accent); }
.tests-promo .info { flex: 1; min-width: 0; }
.tests-promo .info h2 { font-size: 1rem; font-weight: 700; }
.tests-promo .info p { color: var(--text-dim); font-size: 0.86rem; }
.tests-promo .btn { flex-shrink: 0; }
@media (max-width: 720px) {
  .tests-promo { flex-wrap: wrap; }
}

/* ============================================================
   Tutor graceful fallback — hidden when no backend is reachable
   ============================================================ */
body.no-tutor .tutor-open,
body.no-tutor .ask-ai-lesson,
body.no-tutor .tutor-drawer { display: none !important; }

/* ============================================================
   Design pop: dot-grid backdrop, heading accents, card lift
   ============================================================ */
body {
  background-image: radial-gradient(var(--dot) 1px, transparent 1px);
  background-size: 26px 26px;
}
.navbar, .sidebar, .mobile-topbar { background-image: none; background-color: var(--bg); }

.dash-header h1::after,
.lesson-header h1::after {
  content: "";
  display: block;
  width: 58px;
  height: 4px;
  border-radius: 2px;
  margin-top: 12px;
  background: var(--accent);
}
.lesson-header h1::after { margin-top: 10px; }

.glass.hoverable:hover { transform: translateY(-2px); box-shadow: 0 6px 18px rgba(0, 0, 0, 0.18); }
.glass.hoverable { transition: background 0.2s ease, border-color 0.2s ease, transform 0.2s ease, box-shadow 0.2s ease; }

.btn-lg { padding: 14px 32px; font-size: 1.02rem; }

/* ============================================================
   MCQ exam flow
   ============================================================ */
.test-card.soon { opacity: 0.72; }
.test-card.soon h3 .ico { color: var(--text-faint); }

/* pre-exam chooser */
.exam-intro {
  padding: 44px 32px;
  text-align: center;
  margin-bottom: 30px;
}
.exam-intro .ei-icon {
  width: 56px; height: 56px;
  margin: 0 auto 16px;
  border-radius: 50%;
  background: var(--success-soft);
  display: flex; align-items: center; justify-content: center;
}
.exam-intro .ei-icon .ico { width: 26px; height: 26px; color: var(--success); }
.exam-intro h2 { font-size: 1.45rem; margin-bottom: 18px; }
.ei-facts {
  list-style: none;
  margin: 0 auto 26px;
  max-width: 460px;
  text-align: left;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.ei-facts li {
  display: flex;
  align-items: flex-start;
  gap: 10px;
  color: var(--text-dim);
  font-size: 0.93rem;
}
.ei-facts .ico { width: 16px; height: 16px; color: var(--accent); flex-shrink: 0; margin-top: 3px; }
.ei-modes { display: flex; gap: 14px; justify-content: center; flex-wrap: wrap; }
.ei-note { margin-top: 16px; color: var(--text-faint); font-size: 0.82rem; }

/* sticky exam bar + question palette */
.test-sticky .ts-row { display: flex; align-items: center; gap: 16px; }
.q-palette {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px solid var(--border);
}
.pal-chip {
  width: 30px; height: 26px;
  border-radius: 6px;
  border: 1px solid var(--border);
  background: transparent;
  color: var(--text-faint);
  font-size: 0.72rem;
  font-weight: 600;
  font-family: var(--mono);
  transition: border-color 0.15s, background 0.15s, color 0.15s;
}
.pal-chip:hover { background: var(--surface-strong); color: var(--text); }
.pal-chip.answered { background: var(--accent); border-color: var(--accent); color: #fff; }
.pal-chip.chip-right { background: var(--success-soft); border-color: var(--success); color: var(--success); }
.pal-chip.chip-wrong { background: var(--danger-soft); border-color: var(--danger); color: var(--danger); }
.pal-chip.current { outline: 2px solid var(--accent); outline-offset: 1px; font-weight: 800; }

/* bottom finish panel */
.finish-panel {
  text-align: center;
  padding: 34px 20px 12px;
  border-top: 1px solid var(--border);
  margin-top: 10px;
}
.finish-panel p { color: var(--text-dim); font-size: 0.92rem; margin-bottom: 16px; }

/* result panel tweaks */
.result-panel .r-hint {
  margin-top: 18px;
  color: var(--text-faint);
  font-size: 0.85rem;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 7px;
}
.result-panel .r-hint .ico { width: 14px; height: 14px; color: var(--accent); }

/* Ask-AI button inside review cards */
.review-ask { margin-left: auto; }

/* ============================================================
   One-question-at-a-time exam navigation (Bluebook style)
   ============================================================ */
.q-hidden { display: none !important; }
.exam-nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 18px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--border);
}
.exam-nav .nav-counter { font-weight: 700; font-size: 0.95rem; }
.exam-nav .btn[disabled] { opacity: 0.35; }
#testQHost .q-card { margin-bottom: 0; border: none; padding: 8px 0 0; background: transparent; }
#testQHost .q-card .q-text { font-size: 1.05rem; }
#testQHost .q-option { padding: 14px 16px; }

/* ============================================================
   Java Quick Reference — floating, draggable, resizable window
   ============================================================ */
.qr-window {
  position: fixed;
  top: 84px;
  right: 26px;
  width: min(480px, 92vw);
  height: 440px;
  min-width: 300px;
  min-height: 220px;
  max-width: 96vw;
  max-height: 88vh;
  background: var(--bg-elevated);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius);
  box-shadow: 0 14px 44px rgba(0, 0, 0, 0.35);
  z-index: 260;
  display: none;
  flex-direction: column;
  resize: both;            /* stretch & warp from the corner */
  overflow: hidden;
}
.qr-window.open { display: flex; }
.qr-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
  cursor: move;
  user-select: none;
  background: var(--surface-strong);
  flex-shrink: 0;
}
.qr-head .qr-name { display: inline-flex; align-items: center; gap: 8px; font-weight: 700; font-size: 0.9rem; }
.qr-head .qr-name .ico { width: 15px; height: 15px; color: var(--accent); }
.qr-head .icon-btn { width: 28px; height: 28px; border: none; }
.qr-body {
  flex: 1;
  overflow: auto;
  padding: 14px 16px;
  font-family: var(--mono);
  font-size: 0.78rem;
  line-height: 1.6;
  color: var(--text-dim);
}
.qr-body h4 {
  font-family: var(--font);
  color: var(--accent);
  font-size: 0.85rem;
  margin: 16px 0 6px;
  padding-bottom: 4px;
  border-bottom: 1px solid var(--border);
}
.qr-body h4.qr-title { color: var(--text); font-size: 0.95rem; margin-top: 0; }
.qr-body .qr-line { white-space: pre-wrap; word-break: break-word; }

/* ============================================================
   Progress / statistics page
   ============================================================ */
.stats-wrap { padding-bottom: 80px; }
.ov-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 16px;
  margin: 26px 0 34px;
}
.ov-card { padding: 20px 22px; }
.ov-card .ov-label { font-size: 0.78rem; font-weight: 700; text-transform: uppercase; letter-spacing: 0.06em; color: var(--text-faint); margin-bottom: 8px; }
.ov-card .ov-num { font-size: 1.7rem; font-weight: 800; margin-bottom: 8px; }
.ov-card .ov-sub { font-size: 0.8rem; color: var(--text-faint); }

.topic-table-head,
.topic-row {
  display: grid;
  grid-template-columns: minmax(180px, 1.4fr) 1fr 70px 120px;
  gap: 16px;
  align-items: center;
  padding: 11px 4px;
}
.topic-table-head {
  font-size: 0.72rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.07em;
  color: var(--text-faint);
  border-bottom: 1px solid var(--border);
}
.topic-row { border-bottom: 1px solid var(--border); }
.topic-row:last-child { border-bottom: none; }
.topic-row .tr-name { font-weight: 600; font-size: 0.92rem; }
.topic-row .tr-name .tr-n { display: block; font-weight: 400; font-size: 0.75rem; color: var(--text-faint); }
.topic-row .tr-acc { font-family: var(--mono); font-weight: 600; font-size: 0.9rem; text-align: right; }
.topic-row .fill.strong { background: var(--success); }
.topic-row .fill.needs { background: var(--warning); }
.topic-row .fill.weak { background: var(--danger); }
.topic-row .fill.nodata { background: var(--border-strong); }

.chip {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 4px 12px;
  border-radius: 999px;
  font-size: 0.75rem;
  font-weight: 700;
  white-space: nowrap;
}
.chip.strong { background: var(--success-soft); color: var(--success); border: 1px solid var(--success); }
.chip.needs { background: rgba(234, 179, 8, 0.12); color: var(--warning); border: 1px solid var(--warning); }
.chip.weak { background: var(--danger-soft); color: var(--danger); border: 1px solid var(--danger); }
.chip.nodata { background: transparent; color: var(--text-faint); border: 1px solid var(--border); }

.workon-section { margin-top: 44px; }
.workon-card { padding: 22px 24px; margin-bottom: 16px; }
.workon-card .wo-head { display: flex; align-items: center; justify-content: space-between; gap: 12px; flex-wrap: wrap; margin-bottom: 12px; }
.workon-card h3 { font-size: 1.02rem; }
.wo-includes { display: flex; flex-wrap: wrap; gap: 7px; margin-bottom: 14px; }
.wo-includes span {
  font-size: 0.78rem;
  color: var(--text-dim);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 3px 11px;
}
.wo-lessons { display: flex; align-items: center; flex-wrap: wrap; gap: 10px; }
.wo-review { font-size: 0.8rem; font-weight: 700; color: var(--text-faint); }
.wo-lesson {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.83rem;
  font-weight: 600;
  color: var(--accent);
  border: 1px solid var(--border);
  border-radius: 999px;
  padding: 5px 13px;
  transition: background 0.15s, border-color 0.15s;
}
.wo-lesson:hover { background: var(--surface-strong); }
.wo-lesson .ico { width: 13px; height: 13px; }
.workon-empty { text-align: center; padding: 44px 24px; color: var(--text-dim); }
.workon-empty .ico { width: 30px; height: 30px; color: var(--accent); display: block; margin: 0 auto 12px; }
.workon-empty p { max-width: 460px; margin: 0 auto 18px; }

@media (max-width: 720px) {
  .topic-table-head { display: none; }
  .topic-row { grid-template-columns: 1fr 70px 100px; }
  .topic-row .progress-bar { display: none; }
  .exam-nav .btn { padding: 8px 12px; }
}

@media (max-width: 720px) {
  .test-sticky .ts-row { flex-wrap: wrap; gap: 10px; }
  .test-sticky .ts-row .progress-bar { flex-basis: 100%; order: 3; }
  .ei-modes .btn-lg { width: 100%; }
}

/* ============================================================
   Legal pages, legal footer & cookie notice
   ============================================================ */
.legal { max-width: 780px; padding-top: 56px; padding-bottom: 40px; }
.legal h1 { font-size: clamp(1.8rem, 4vw, 2.4rem); font-weight: 800; letter-spacing: -0.015em; margin-bottom: 4px; }
.legal-updated { color: var(--text-faint); font-size: 0.85rem; margin-bottom: 28px; }
.legal h2 { font-size: 1.25rem; font-weight: 700; margin: 34px 0 10px; }
.legal h3 { font-size: 1rem; font-weight: 600; margin: 20px 0 6px; }
.legal p { color: var(--text-dim); font-size: 0.95rem; margin-bottom: 12px; }
.legal ul { margin: 0 0 12px 22px; }
.legal li { color: var(--text-dim); font-size: 0.95rem; margin-bottom: 8px; }
.legal strong { color: var(--text); font-weight: 600; }
.legal a { color: var(--accent); }
.legal a:hover { text-decoration: underline; }

/* Checkbox row (signup age confirmation) */
.check-row {
  display: flex; align-items: flex-start; gap: 10px;
  text-align: left; margin-bottom: 18px; cursor: pointer;
}
.check-row input[type="checkbox"] {
  width: 17px; height: 17px; margin-top: 3px; flex-shrink: 0;
  accent-color: var(--accent); cursor: pointer;
}
.check-row span { font-size: 0.88rem; color: var(--text-dim); }

/* Slim legal footer injected on pages without a full <footer> */
.app-footer {
  padding: 26px 16px 22px;
  text-align: center;
  font-size: 0.8rem;
  color: var(--text-faint);
}
.app-footer a { color: var(--text-dim); transition: color 0.2s; }
.app-footer a:hover { color: var(--text); }
.app-footer .dot { margin: 0 8px; }

/* Cookie notice banner (first visit). Deliberately in normal document flow
   (not position:fixed) so it displaces the page instead of floating on top
   of it — a fixed overlay could otherwise cover content underneath it, e.g.
   the "you agree to our Terms / Privacy Policy" line on signup. */
.cookie-banner {
  position: relative;
  z-index: 500;
  display: flex; align-items: center; gap: 16px;
  padding: 12px 4%;
  background: var(--surface);
  border-bottom: 1px solid var(--border);
}
.cookie-banner p { font-size: 0.85rem; color: var(--text-dim); flex: 1; margin: 0; }
.cookie-banner a { color: var(--accent); }
.cookie-banner a:hover { text-decoration: underline; }
.cookie-banner .btn { padding: 8px 18px; font-size: 0.85rem; flex-shrink: 0; }
@media (max-width: 560px) {
  .cookie-banner { flex-direction: column; align-items: stretch; text-align: center; }
}

/* WCAG AA contrast fixes: --accent (4.38:1) and --danger (4.28:1) both
   pass fine as button fills / borders (>=3:1 non-text threshold) but fall
   just short of the 4.5:1 normal-text threshold when read as body copy on
   dark backgrounds. Scoped overrides here so buttons/icons/chips elsewhere
   keep the original brand colors untouched. */
[data-theme="dark"] .legal a,
[data-theme="dark"] .cookie-banner a {
  color: #62a0ff;
}
[data-theme="dark"] .feedback.bad,
[data-theme="dark"] .t-msg.err,
[data-theme="dark"] .q-option.wrong .opt-key,
[data-theme="dark"] .test-sticky .timer.low,
[data-theme="dark"] .result-panel .r-score.bad {
  color: #f16161;
}

/* Visually hidden but available to assistive tech — used for structural
   headings that would be visually redundant (e.g. a "Course units" label
   above a list that's already visually obvious from layout/context). */
.sr-only {
  position: absolute;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* Skip-to-content link: hidden until keyboard-focused, then pinned top-left */
.skip-link {
  position: absolute;
  left: 8px; top: -60px;
  z-index: 3000;
  background: var(--accent);
  color: #fff;
  padding: 10px 18px;
  border-radius: var(--radius-sm);
  font-weight: 600;
  font-size: 0.9rem;
  transition: top 0.15s ease;
}
.skip-link:focus {
  top: 8px;
}

/* Visible keyboard-focus ring — only for :focus-visible so mouse/touch
   clicks are unaffected; inputs already have their own focus treatment. */
a:focus-visible,
button:focus-visible,
[tabindex]:focus-visible,
.icon-btn:focus-visible,
.btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}