/*
═══════════════════════════════════════════════════════════════
SCISPARK LESSON SHARED CSS
═══════════════════════════════════════════════════════════════
File: /public/lesson-shell.css (Vercel auto-served at /lesson-shell.css)
Type: SHARED stylesheet — used by ALL lesson HTML files
Source: extracted from SCISPARK_LESSON_SHELL_v1 → v2 (B-mode shared)
Date: 2026-05-11
Status: PERMANENT LOCKED — change here propagates to ALL lessons

Includes:
  - All CSS variables (v3.1 design tokens)
  - Layout (top-nav, sidebar, main-content)
  - 5-screen system (HOOK/LEARN/TRY/TEST/WRAP)
  - Note slide system (banner, sub-boxes, definition, summary)
  - Question blocks (MCQ, Hints, Answer reveal)
  - EN↔ZH bilingual toggle
  - Professor P bubble animation
  - Mobile responsive
═══════════════════════════════════════════════════════════════
*/

:root {
  /* Backgrounds */
  --bg:        #FBF8F4;
  --bg-2:      #F4EFE7;
  --bg-card:   #ffffff;

  /* Text */
  --ink:       #171413;
  --ink-2:     #3a342f;
  --ink-3:     #6b6358;

  /* Borders */
  --line:      #E6DFD3;
  --line-2:    #D9D0BF;

  /* Brand orange */
  --accent:      #EA580C;
  --accent-soft: #FFE9D6;
  --accent-ink:  #7a2e08;

  /* Semantic */
  --ok:        #2E7D5B;
  --ok-bg:     #d9eed9;
  --ok-text:   #2a6a2a;
  --warn:      #a32d2d;
  --warn-bg:   #fce8e6;

  /* Fonts */
  --ff-display: 'Instrument Serif', 'Times New Roman', serif;
  --ff-body:    'Inter', -apple-system, sans-serif;
  --ff-mono:    'JetBrains Mono', monospace;
  --ff-zh:      'Noto Sans SC', 'PingFang SC', system-ui, sans-serif;
}

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

html, body {
  background: var(--bg); color: var(--ink-2);
  font-family: var(--ff-body); font-size: 15px; line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* ─── CONTENT PROTECTION ─── */
.screen, .vocab-card, .question-block, .definition-text, .summary-text,
.concept-desc, .question-text, .answer-reveal-text, .mistake-text,
.wrap-point, .card-title, .vocab-def, .hook-scenario {
  -webkit-user-select: none; -moz-user-select: none;
  -ms-user-select: none; user-select: none;
}
input, textarea {
  user-select: text; -webkit-user-select: text; -moz-user-select: text;
}
img, svg { -webkit-user-drag: none; user-drag: none; }
@media print {
  body > *:not(.print-notice) { display: none !important; }
  .print-notice { display: block !important; padding: 60px; font-size: 24px;
    text-align: center; font-family: var(--ff-display); }
}
.print-notice { display: none; }

/* ─── LAYOUT ─── */
.app { display: flex; flex-direction: column; min-height: 100vh; }

/* ─── TOP NAV ─── */
.top-nav {
  background: var(--ink); color: white;
  padding: 0 24px; height: 56px;
  display: flex; align-items: center; gap: 12px;
  position: sticky; top: 0; z-index: 100;
  border-bottom: 1px solid rgba(255,255,255,0.06);
}
.nav-logo svg { width: 28px; height: 28px; }
.nav-brand { font-family: var(--ff-body); font-weight: 700; font-size: 17px; }
.nav-brand .spark { color: var(--accent); }
.nav-meta {
  font-family: var(--ff-mono); font-size: 10px;
  color: rgba(255,255,255,0.45); letter-spacing: 0.1em;
  text-transform: uppercase;
}
.nav-badge {
  background: rgba(234,88,12,0.18); color: var(--accent);
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.1em; text-transform: uppercase;
  padding: 3px 8px; border-radius: 4px;
  border: 1px solid rgba(234,88,12,0.3);
}
.nav-spacer { flex: 1; }

/* ─── DASHBOARD BACK LINK (locked convention 2026-05-10) ─── */
.nav-back {
  font-family: var(--ff-mono); font-size: 10px; font-weight: 600;
  color: rgba(255,255,255,0.55); letter-spacing: 0.06em;
  text-decoration: none; padding: 5px 10px; border-radius: 6px;
  border: 1px solid rgba(255,255,255,0.12);
  transition: all 0.15s;
}
.nav-back:hover { color: white; border-color: rgba(255,255,255,0.3); }

/* Streak counter */
.nav-streak {
  display: flex; align-items: center; gap: 5px;
  font-family: var(--ff-mono); font-size: 11px; font-weight: 700;
  color: rgba(255,255,255,0.85);
  background: rgba(234,88,12,0.15); padding: 4px 10px; border-radius: 999px;
  border: 1px solid rgba(234,88,12,0.25);
}
.nav-streak-flame { font-size: 13px; }

/* ─── ENGLISH-ONLY MODE: hide all Chinese elements ─── */
body:not(.bilingual) .zh,
body:not(.bilingual) .screen-title-zh,
body:not(.bilingual) .card-zh,
body:not(.bilingual) .vocab-zh,
body:not(.bilingual) .lesson-footer-zh,
body:not(.bilingual) .ai-prompt-btn-zh,
body:not(.bilingual) .badge-reveal-zh,
body:not(.bilingual) .surprise-zh,
body:not(.bilingual) .prof-p-bubble-zh,
body:not(.bilingual) .lang-toggle {
  display: none !important;
}

/* Language toggle pill */
.lang-toggle {
  display: flex; gap: 0;
  background: rgba(255,255,255,0.08);
  border-radius: 999px; padding: 2px;
}
.lang-btn {
  background: transparent; color: rgba(255,255,255,0.6); border: none;
  padding: 5px 12px; border-radius: 999px;
  font-family: var(--ff-body); font-size: 11px; font-weight: 600;
  cursor: pointer; transition: all 0.15s;
}
.lang-btn.active { background: var(--accent); color: white; }

/* ─── BODY LAYOUT ─── */
.body-wrap { display: flex; flex: 1; }

/* ─── SIDEBAR ─── */
.sidebar {
  width: 240px; flex-shrink: 0;
  background: var(--bg-2);
  border-right: 1px solid var(--line);
  padding: 20px 0;
  position: sticky; top: 56px; height: calc(100vh - 56px);
  overflow-y: auto;
}
.sidebar-unit { padding: 0 16px 16px; border-bottom: 1px solid var(--line); margin-bottom: 8px; }
.sidebar-unit-label {
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--ink-3); margin-bottom: 4px;
}
.sidebar-unit-title {
  font-family: var(--ff-display); font-size: 14px;
  color: var(--ink); line-height: 1.3;
}
.screen-nav-item {
  display: flex; align-items: flex-start; gap: 10px;
  padding: 10px 16px; cursor: pointer; transition: background 0.12s;
  border-left: 3px solid transparent; text-decoration: none;
}
.screen-nav-item:hover { background: rgba(234,88,12,0.06); }
.screen-nav-item.active {
  background: var(--accent-soft); border-left-color: var(--accent);
}
.screen-nav-item.locked { opacity: 0.45; cursor: default; pointer-events: none; }
.screen-num {
  width: 22px; height: 22px; border-radius: 50%; flex-shrink: 0;
  background: var(--line-2); color: var(--ink-3);
  display: flex; align-items: center; justify-content: center;
  font-size: 10px; font-weight: 700; margin-top: 1px;
}
.screen-nav-item.active .screen-num { background: var(--accent); color: white; }
.screen-nav-item.done .screen-num { background: var(--ok-bg); color: var(--ok-text); }
.screen-nav-labels { flex: 1; }
.screen-nav-main {
  font-size: 12px; font-weight: 600; color: var(--ink);
  text-transform: uppercase; letter-spacing: 0.06em;
}
.screen-nav-item.active .screen-nav-main { color: var(--accent); }
.screen-nav-sub {
  font-family: var(--ff-mono); font-size: 9px; color: var(--ink-3);
  letter-spacing: 0.04em; margin-top: 1px;
}
.sidebar-progress {
  padding: 14px 16px; margin-top: 8px;
  border-top: 1px solid var(--line);
}
.progress-label {
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--ink-3); margin-bottom: 6px;
  display: flex; justify-content: space-between;
}
.progress-bar {
  height: 4px; background: var(--line); border-radius: 999px; overflow: hidden;
}
.progress-fill {
  height: 100%; background: var(--accent); border-radius: 999px;
  transition: width 0.3s ease;
}

/* ─── MAIN CONTENT ─── */
.main-content { flex: 1; overflow-y: auto; }
.screen { display: none; padding: 32px clamp(20px,4vw,48px) 64px; max-width: 820px; }
.screen.active { display: block; animation: fadeIn 0.18s ease; }
@keyframes fadeIn { from { opacity: 0; transform: translateY(6px); } to { opacity: 1; } }

.screen-header { margin-bottom: 28px; }
.screen-eyebrow {
  font-family: var(--ff-mono); font-size: 10px; font-weight: 700;
  letter-spacing: 0.18em; text-transform: uppercase;
  color: var(--accent); margin-bottom: 6px;
}
.screen-title {
  font-family: var(--ff-display); font-size: clamp(28px,4vw,40px);
  font-weight: 400; color: var(--ink); line-height: 1.1;
  letter-spacing: -0.02em; margin-bottom: 4px;
}
.screen-title-zh {
  font-family: var(--ff-zh); font-size: 14px; color: var(--ink-3);
}
.screen-desc {
  font-size: 14px; color: var(--ink-3); margin-top: 10px;
  max-width: 560px; line-height: 1.55;
}

/* ─── CARDS ─── */
.card {
  background: var(--bg-card); border: 1px solid var(--line);
  border-radius: 14px; padding: 24px; margin-bottom: 18px;
}
.card-accent { border-left: 4px solid var(--accent); }
.card-ok { border-left: 4px solid var(--ok); }
.card-title {
  font-family: var(--ff-display); font-size: 20px;
  color: var(--ink); margin-bottom: 8px; line-height: 1.2;
}
.card-zh {
  font-family: var(--ff-zh); font-size: 12px; color: var(--ink-3);
  margin-bottom: 10px;
}

/* ─── ZH GLOSS INLINE ─── */
.zh {
  font-family: var(--ff-zh); font-size: 11px; color: var(--ink-3);
  margin-left: 4px;
}

/* ─── ZH MODE (MODE 2: full Chinese primary) ─── */
body.zh-mode .zh {
  font-size: 14px; color: var(--ink); margin-left: 0;
  display: inline-block; margin-top: 2px;
}
body.zh-mode .vocab-zh, body.zh-mode .card-zh, body.zh-mode .screen-title-zh {
  font-size: 22px; color: var(--ink); font-weight: 600;
}
body.zh-mode .vocab-word, body.zh-mode .card-title strong,
body.zh-mode .screen-title {
  font-size: 14px; color: var(--ink-3); font-weight: 400; opacity: 0.7;
}

/* ─── VOCAB CARDS ─── */
.vocab-grid {
  display: grid; grid-template-columns: repeat(auto-fill, minmax(160px, 1fr));
  gap: 10px; margin-bottom: 20px;
}
.vocab-card {
  background: var(--bg-card); border: 1px solid var(--line);
  border-radius: 10px; padding: 14px 16px;
  border-top: 3px solid var(--accent);
}
.vocab-word { font-weight: 600; font-size: 14px; color: var(--ink); }
.vocab-zh {
  font-family: var(--ff-zh); font-size: 12px; color: var(--accent); margin-top: 2px;
}
.vocab-def { font-size: 11px; color: var(--ink-3); margin-top: 5px; line-height: 1.4; }

/* ─── CONCEPT SPLIT ─── */
.concept-split {
  display: grid; grid-template-columns: 1fr 1fr; gap: 14px;
  margin-bottom: 18px;
}
@media (max-width: 600px) { .concept-split { grid-template-columns: 1fr; } }
.concept-box {
  background: var(--bg-card); border: 1.5px solid var(--line);
  border-radius: 12px; padding: 20px; text-align: center;
}
.concept-box.mint { border-color: #2E7D32; background: #f0fff0; }
.concept-box.peach { border-color: #E97200; background: #fff7ed; }
.concept-box.cyan { border-color: #0090B8; background: #f0faff; }
.concept-icon { margin-bottom: 10px; }
.concept-label { font-weight: 700; font-size: 14px; margin-bottom: 3px; }
.concept-box.mint .concept-label { color: #2E7D32; }
.concept-box.peach .concept-label { color: #E97200; }
.concept-box.cyan .concept-label { color: #0090B8; }
.concept-desc { font-size: 12px; color: var(--ink-3); line-height: 1.4; }
.concept-examples {
  margin-top: 10px; font-size: 11px; color: var(--ink-3);
  background: rgba(0,0,0,0.03); border-radius: 6px; padding: 6px 10px;
}

/* ─── DEFINITION BOX ─── */
.definition-box {
  background: #EDF6FD; border: 1.5px solid #0090B8;
  border-radius: 10px; padding: 16px 20px; margin-bottom: 18px;
}
.definition-label {
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: #0090B8; margin-bottom: 6px;
}
.definition-text { font-size: 15px; color: var(--ink); line-height: 1.5; }
.definition-text strong { color: var(--accent); }

/* ─── SUMMARY BOX ─── */
.summary-box {
  background: #F5F0E4; border: 1px solid var(--line-2);
  border-radius: 10px; padding: 16px 20px; margin-bottom: 18px;
  text-align: center;
}
.summary-label {
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--ink-3); margin-bottom: 8px;
}
.summary-text {
  font-family: var(--ff-display); font-size: 18px;
  color: var(--ink); line-height: 1.3;
}

/* ─── COMMON MISTAKE ─── */
.mistake-box {
  background: var(--warn-bg); border: 1.5px solid var(--warn);
  border-radius: 10px; padding: 14px 18px; margin-bottom: 18px;
}
.mistake-label {
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--warn); margin-bottom: 6px;
}
.mistake-text { font-size: 13px; color: var(--ink-2); }

/* ─── IMAGE PLACEHOLDER (DALL-E future fills) ─── */
.img-placeholder {
  background: var(--bg-2); border: 2px dashed var(--line-2);
  border-radius: 12px; padding: 24px;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  min-height: 160px; margin: 14px 0;
  text-align: center;
}
.img-placeholder-num {
  font-family: var(--ff-mono); font-size: 10px; font-weight: 700;
  letter-spacing: 0.12em; text-transform: uppercase;
  color: var(--accent); background: var(--accent-soft);
  padding: 3px 10px; border-radius: 999px; margin-bottom: 8px;
}
.img-placeholder-desc {
  font-size: 12px; color: var(--ink-3); max-width: 320px; line-height: 1.5;
}

/* ─── QUESTION BLOCKS ─── */
.question-block {
  background: var(--bg-card); border: 1px solid var(--line);
  border-radius: 12px; margin-bottom: 16px; overflow: hidden;
}
.question-header {
  display: flex; align-items: center; gap: 10px;
  padding: 12px 18px; background: var(--bg-2);
  border-bottom: 1px solid var(--line);
}
.q-number {
  background: var(--accent); color: white;
  font-family: var(--ff-mono); font-size: 10px; font-weight: 700;
  padding: 3px 8px; border-radius: 4px; letter-spacing: 0.06em;
}
.q-topic { font-size: 12px; color: var(--ink-3); flex: 1; }
.q-marks {
  font-family: var(--ff-mono); font-size: 10px; font-weight: 700;
  color: var(--ink-3); letter-spacing: 0.08em;
}
.question-body { padding: 16px 18px; }
.question-text { font-size: 14px; color: var(--ink); margin-bottom: 12px; line-height: 1.55; }
.mcq-options { display: flex; flex-direction: column; gap: 8px; }
.mcq-option {
  display: flex; align-items: flex-start; gap: 10px;
  padding: 10px 14px; border: 1.5px solid var(--line);
  border-radius: 8px; cursor: pointer; font-size: 13px;
  transition: all 0.12s; color: var(--ink-2);
}
.mcq-option:hover { border-color: var(--accent); background: var(--accent-soft); }
.mcq-option.selected { border-color: var(--accent); background: var(--accent-soft); color: var(--ink); }
.mcq-option.correct { border-color: var(--ok); background: var(--ok-bg); color: var(--ok-text); }
.mcq-option.wrong { border-color: var(--warn); background: var(--warn-bg); }
.opt-letter {
  width: 22px; height: 22px; border-radius: 50%; flex-shrink: 0;
  background: var(--line); color: var(--ink-3);
  display: flex; align-items: center; justify-content: center;
  font-size: 11px; font-weight: 700;
}
.mcq-option.selected .opt-letter { background: var(--accent); color: white; }
.mcq-option.correct .opt-letter { background: var(--ok); color: white; }

/* ─── HINT (Level system: data-show-level) ─── */
.hint-box {
  background: var(--accent-soft); border: 1px solid var(--accent);
  border-radius: 8px; padding: 10px 14px; margin-top: 10px;
  font-size: 12px; color: var(--accent-ink); display: none;
}
.hint-box.show { display: block; }
.hint-label {
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--accent); margin-bottom: 4px;
}
/* Level system: hide hint controls based on user level */
body[data-user-level="3"] .hint-trigger { display: none !important; }
body[data-user-level="3"] .hint-box { display: none !important; }
body[data-user-level="1"] .hint-box { display: block; }

/* ─── SHORT ANSWER ─── */
.short-input {
  width: 100%; padding: 10px 14px; border: 1.5px solid var(--line);
  border-radius: 8px; font-family: var(--ff-body); font-size: 14px;
  color: var(--ink); background: var(--bg-card); outline: none;
  transition: border-color 0.15s; resize: vertical; min-height: 60px;
}
.short-input:focus { border-color: var(--accent); }

/* Auto-save indicator */
.save-indicator {
  font-family: var(--ff-mono); font-size: 9px; color: var(--ok-text);
  margin-top: 4px; opacity: 0; transition: opacity 0.3s;
}
.save-indicator.show { opacity: 1; }

/* ─── ANSWER REVEAL ─── */
.answer-reveal {
  background: var(--ok-bg); border: 1px solid var(--ok);
  border-radius: 8px; padding: 12px 16px; margin-top: 10px; display: none;
}
.answer-reveal.show { display: block; }
.answer-reveal-label {
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--ok-text); margin-bottom: 4px;
}
.answer-reveal-text { font-size: 13px; color: var(--ok-text); }
.source-note { font-size: 11px; color: var(--ink-3); margin-top: 6px; font-style: italic; }

/* ─── BUTTONS ─── */
.btn {
  display: inline-flex; align-items: center; justify-content: center; gap: 8px;
  padding: 11px 22px; border-radius: 999px;
  font-family: var(--ff-body); font-size: 13px; font-weight: 600;
  border: none; cursor: pointer; text-decoration: none; transition: all 0.15s;
}
.btn-primary { background: var(--accent); color: white; }
.btn-primary:hover { background: #c2460a; }
.btn-secondary { background: transparent; color: var(--ink-3); border: 1.5px solid var(--line); }
.btn-secondary:hover { border-color: var(--accent); color: var(--accent); }
.btn-sm { padding: 7px 14px; font-size: 12px; }
.btn-row { display: flex; gap: 10px; align-items: center; margin-top: 20px; flex-wrap: wrap; }

/* ─── FLOW ARROW ─── */
.flow-row {
  display: flex; align-items: center; gap: 10px;
  margin: 14px 0; flex-wrap: wrap;
}
.flow-box {
  background: var(--bg-card); border: 1.5px solid var(--line);
  border-radius: 8px; padding: 10px 16px;
  font-size: 13px; font-weight: 600; color: var(--ink);
  text-align: center; flex: 1; min-width: 100px;
}
.flow-box.accent { border-color: var(--accent); background: var(--accent-soft); color: var(--accent-ink); }
.flow-arrow { color: var(--accent); font-size: 20px; flex-shrink: 0; }

/* ─── WRAP SCREEN ─── */
.wrap-summary {
  background: var(--ink); color: white;
  border-radius: 14px; padding: 28px; margin-bottom: 20px;
}
.wrap-summary h3 {
  font-family: var(--ff-display); font-size: 22px; font-weight: 400;
  color: white; margin-bottom: 14px;
}
.wrap-point {
  display: flex; align-items: flex-start; gap: 10px;
  margin-bottom: 10px; font-size: 14px; color: rgba(255,255,255,0.85);
}
.wrap-dot {
  width: 6px; height: 6px; border-radius: 50%;
  background: var(--accent); flex-shrink: 0; margin-top: 6px;
}
.cliffhanger {
  background: var(--accent); color: white;
  border-radius: 14px; padding: 22px 24px; margin-top: 20px;
}
.cliff-label {
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: rgba(255,255,255,0.7); margin-bottom: 8px;
}
.cliff-text {
  font-family: var(--ff-display); font-size: 18px;
  color: white; line-height: 1.3;
}

/* Stay Curious sign-off */
.stay-curious {
  text-align: center; margin: 28px 0 20px;
  padding: 24px 20px;
  border-top: 1px solid var(--line); border-bottom: 1px solid var(--line);
}
.stay-curious-quote {
  font-family: var(--ff-display); font-size: 22px; color: var(--accent);
  margin-bottom: 8px; font-style: italic;
}
.stay-curious-author {
  font-family: var(--ff-mono); font-size: 10px;
  color: var(--ink-3); letter-spacing: 0.12em; text-transform: uppercase;
}

/* First Lab Badge reveal */
.badge-reveal {
  background: linear-gradient(135deg, #FFE9D6 0%, #ffffff 100%);
  border: 2px solid var(--accent); border-radius: 14px;
  padding: 24px; text-align: center; margin-bottom: 20px;
  position: relative; overflow: hidden;
}
.badge-reveal-icon {
  width: 80px; height: 80px; border-radius: 50%;
  background: var(--accent); margin: 0 auto 12px;
  display: flex; align-items: center; justify-content: center;
  animation: badgePulse 2s ease-in-out infinite;
}
@keyframes badgePulse {
  0%, 100% { transform: scale(1); box-shadow: 0 0 0 0 rgba(234,88,12,0.4); }
  50% { transform: scale(1.05); box-shadow: 0 0 0 12px rgba(234,88,12,0); }
}
.badge-reveal-name {
  font-family: var(--ff-display); font-size: 22px; color: var(--ink);
  margin-bottom: 4px;
}
.badge-reveal-zh {
  font-family: var(--ff-zh); font-size: 13px; color: var(--ink-3);
  margin-bottom: 10px;
}
.badge-reveal-desc { font-size: 13px; color: var(--ink-3); }

/* XP display in WRAP */
.xp-wrap {
  display: flex; gap: 12px; justify-content: center; margin-bottom: 20px;
  flex-wrap: wrap;
}
.xp-stat {
  background: var(--bg-card); border: 1px solid var(--line);
  border-radius: 10px; padding: 12px 18px; text-align: center;
  min-width: 100px;
}
.xp-stat-value {
  font-family: var(--ff-display); font-size: 22px;
  color: var(--accent); font-weight: 400;
}
.xp-stat-label {
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.1em; text-transform: uppercase;
  color: var(--ink-3); margin-top: 2px;
}

/* Knowt placeholder */
.knowt-placeholder {
  background: var(--bg-2); border: 2px dashed var(--accent);
  border-radius: 12px; padding: 20px; margin-bottom: 18px;
  text-align: center;
}
.knowt-label {
  font-family: var(--ff-mono); font-size: 10px; font-weight: 700;
  letter-spacing: 0.14em; text-transform: uppercase;
  color: var(--accent); margin-bottom: 8px;
}
.knowt-title {
  font-family: var(--ff-display); font-size: 18px; color: var(--ink);
  margin-bottom: 4px;
}
.knowt-desc { font-size: 12px; color: var(--ink-3); }

/* ─── PROFESSOR P AVATAR (fixed bottom-right) ─── */
.prof-p {
  position: fixed; bottom: 20px; right: 20px; z-index: 200;
}
.prof-p-avatar {
  width: 64px; height: 64px; border-radius: 50%;
  background: var(--accent);
  display: flex; align-items: center; justify-content: center;
  cursor: pointer; box-shadow: 0 4px 16px rgba(234,88,12,0.3);
  transition: transform 0.2s; position: relative;
}
.prof-p-avatar:hover { transform: scale(1.05); }
.prof-p-avatar svg { width: 36px; height: 36px; }
.prof-p-bubble {
  position: absolute; bottom: 80px; right: 0;
  background: white; border: 1.5px solid var(--accent);
  border-radius: 14px 14px 4px 14px;
  padding: 14px 18px; min-width: 220px; max-width: 280px;
  box-shadow: 0 6px 20px rgba(0,0,0,0.08);
  font-size: 13px; color: var(--ink-2); line-height: 1.5;
  display: none; animation: bubbleIn 0.25s ease;
}
@keyframes bubbleIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}
.prof-p-bubble.show { display: block; }
.prof-p-bubble-zh {
  font-family: var(--ff-zh); font-size: 11px; color: var(--ink-3);
  margin-top: 4px;
}
.prof-p-bubble-close {
  position: absolute; top: 6px; right: 8px;
  background: transparent; border: none; cursor: pointer;
  color: var(--ink-3); font-size: 14px;
}

/* ─── PROFESSOR P HOOK VIDEO (HOOK screen top) ─── */
.prof-p-video {
  background: linear-gradient(135deg, #1a1a1a 0%, #2a1a0a 100%);
  border-radius: 14px; aspect-ratio: 16 / 9;
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  margin-bottom: 20px; color: white;
  border: 1px solid rgba(234,88,12,0.3);
  position: relative; overflow: hidden;
}
.prof-p-video-play {
  width: 60px; height: 60px; border-radius: 50%;
  background: var(--accent); display: flex; align-items: center; justify-content: center;
  margin-bottom: 12px; cursor: pointer;
}
.prof-p-video-title {
  font-family: var(--ff-display); font-size: 20px; margin-bottom: 4px;
}
.prof-p-video-meta {
  font-family: var(--ff-mono); font-size: 10px;
  color: rgba(255,255,255,0.5); letter-spacing: 0.12em; text-transform: uppercase;
}

/* ─── AI TUTOR PANEL ─── */
.ai-tutor-trigger {
  background: var(--accent-soft); border: 1px solid var(--accent);
  border-radius: 14px; padding: 14px 18px; margin-bottom: 16px;
  display: flex; align-items: center; gap: 14px; cursor: pointer;
  transition: background 0.15s;
}
.ai-tutor-trigger:hover { background: #ffd9b5; }
.ai-tutor-icon {
  width: 40px; height: 40px; border-radius: 50%;
  background: var(--accent); flex-shrink: 0;
  display: flex; align-items: center; justify-content: center;
}
.ai-tutor-text { flex: 1; }
.ai-tutor-title { font-weight: 600; color: var(--accent-ink); font-size: 14px; }
.ai-tutor-sub { font-size: 11px; color: var(--ink-3); margin-top: 2px; }

.ai-tutor-panel {
  position: fixed; right: 20px; top: 80px; bottom: 100px;
  width: 360px; max-width: calc(100vw - 40px);
  background: white; border: 1px solid var(--line);
  border-radius: 14px; box-shadow: 0 8px 30px rgba(0,0,0,0.12);
  z-index: 250; display: none;
  flex-direction: column;
}
.ai-tutor-panel.open { display: flex; }
.ai-tutor-header {
  padding: 16px 18px; border-bottom: 1px solid var(--line);
  display: flex; align-items: center; gap: 10px;
}
.ai-tutor-header-title {
  font-family: var(--ff-display); font-size: 17px; flex: 1;
}
.ai-tutor-close {
  background: transparent; border: none; cursor: pointer;
  font-size: 18px; color: var(--ink-3);
}
.ai-tutor-body {
  flex: 1; padding: 16px; overflow-y: auto;
}
.ai-tutor-status {
  background: var(--bg-2); border-radius: 10px;
  padding: 12px 14px; margin-bottom: 14px;
  font-size: 12px; color: var(--ink-3); text-align: center;
}
.ai-tutor-status strong { color: var(--accent); }
.ai-prompt-list { display: flex; flex-direction: column; gap: 8px; }
.ai-prompt-btn {
  background: var(--accent-soft); border: 1px solid var(--line);
  border-radius: 10px; padding: 10px 14px;
  text-align: left; cursor: pointer; font-size: 13px;
  color: var(--ink-2); transition: all 0.12s;
}
.ai-prompt-btn:hover { border-color: var(--accent); }
.ai-prompt-btn-zh {
  display: block; font-family: var(--ff-zh); font-size: 11px;
  color: var(--ink-3); margin-top: 4px;
}

/* ─── XP TOAST ─── */
.xp-toast {
  position: fixed; top: 80px; right: 20px; z-index: 300;
  background: var(--accent); color: white;
  padding: 12px 20px; border-radius: 999px;
  font-family: var(--ff-mono); font-weight: 700; font-size: 14px;
  box-shadow: 0 6px 20px rgba(234,88,12,0.4);
  display: none; animation: xpToast 1.6s ease;
}
.xp-toast.show { display: block; }
@keyframes xpToast {
  0% { opacity: 0; transform: translateY(-10px) scale(0.9); }
  15% { opacity: 1; transform: translateY(0) scale(1); }
  85% { opacity: 1; transform: translateY(0) scale(1); }
  100% { opacity: 0; transform: translateY(-6px) scale(0.95); }
}

/* ─── SURPRISE DROP MODAL ─── */
.surprise-modal {
  position: fixed; inset: 0; background: rgba(0,0,0,0.6);
  z-index: 400; display: none;
  align-items: center; justify-content: center;
  animation: fadeIn 0.3s ease;
}
.surprise-modal.show { display: flex; }
.surprise-content {
  background: linear-gradient(135deg, #FFE9D6 0%, #ffffff 100%);
  border: 3px solid var(--accent); border-radius: 20px;
  padding: 40px; max-width: 400px; text-align: center;
  animation: surpriseIn 0.4s cubic-bezier(0.34, 1.56, 0.64, 1);
}
@keyframes surpriseIn {
  from { opacity: 0; transform: scale(0.5); }
  to { opacity: 1; transform: scale(1); }
}
.surprise-emoji { font-size: 64px; margin-bottom: 12px; }
.surprise-title {
  font-family: var(--ff-display); font-size: 28px; color: var(--accent);
  margin-bottom: 8px;
}
.surprise-zh { font-family: var(--ff-zh); font-size: 14px; color: var(--ink-3); margin-bottom: 16px; }
.surprise-text { font-size: 14px; color: var(--ink-2); margin-bottom: 20px; line-height: 1.5; }

/* ─── DIVIDER ─── */
.divider { border: none; border-top: 1px solid var(--line); margin: 22px 0; }

/* ─── FOOTER ─── */
.lesson-footer {
  padding: 24px;
  font-family: var(--ff-mono); font-size: 10px;
  color: var(--ink-3); letter-spacing: 0.06em;
  border-top: 1px solid var(--line);
  text-align: center; line-height: 1.6;
}
.lesson-footer-zh {
  font-family: var(--ff-zh); font-size: 10px; color: var(--ink-3);
  margin-top: 4px;
}

/* ─── LEVEL BADGE ─── */
.level-badge {
  display: inline-flex; align-items: center; gap: 5px;
  font-family: var(--ff-mono); font-size: 9px; font-weight: 700;
  letter-spacing: 0.1em; text-transform: uppercase;
  padding: 3px 8px; border-radius: 4px;
}
.level-1 { background: var(--ok-bg); color: var(--ok-text); }
.level-2 { background: var(--accent-soft); color: var(--accent-ink); }
.level-3 { background: #F3E5F5; color: #6b00a8; }

/* ============================================
   TTS Button — Text-to-speech for paragraphs
   v2.1 — 2026-05-12
   ============================================ */

.tts-row {
  display: flex;
  gap: 10px;
  align-items: flex-start;
  margin: 8px 0;
}

.tts-text {
  flex: 1;
  margin: 0;
}

.tts-btn {
  flex-shrink: 0;
  width: 28px;
  height: 28px;
  border-radius: 50%;
  border: none;
  background: var(--accent);
  color: #ffffff;
  font-size: 11px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-top: 4px;
  transition: transform 0.15s ease, background 0.15s ease;
  user-select: none;
  padding: 0;
}

.tts-btn:hover:not(.tts-disabled):not(.tts-playing) {
  background: var(--accent-ink);
  transform: scale(1.05);
}

.tts-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}

.tts-btn.tts-playing {
  background: var(--accent-ink);
  animation: tts-pulse 1s ease-in-out infinite;
}

.tts-btn.tts-disabled {
  background: var(--bg-2);
  color: var(--ink-3);
  opacity: 0.5;
  cursor: not-allowed;
}

@keyframes tts-pulse {
  0%, 100% { transform: scale(1.0); }
  50%      { transform: scale(1.05); }
}

/* Mobile: tap target should be 44x44 minimum
   (Rule 0 + WCAG); we expand hit area via padding,
   button visual stays 28x28 */
@media (max-width: 768px) {
  .tts-btn {
    width: 32px;
    height: 32px;
    font-size: 12px;
  }
}

/* Prefers-reduced-motion: stop pulse animation */
@media (prefers-reduced-motion: reduce) {
  .tts-btn.tts-playing {
    animation: none;
  }
}

/* ============================================
   DouDou Reaction — animations + bubble + self-assess
   v2.1 — 2026-05-12
   ============================================ */

/* Reaction mini-bubble (above avatar) */
#doudou-reaction-bubble {
  position: absolute;
  bottom: 74px;
  right: 0;
  background: #ffffff;
  border: 2px solid var(--accent);
  border-radius: 12px 12px 4px 12px;
  padding: 7px 13px;
  font-size: 13px;
  font-weight: 700;
  color: var(--ink);
  white-space: nowrap;
  box-shadow: 0 4px 14px rgba(0,0,0,0.12);
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.25s ease;
  z-index: 201;
}
#doudou-reaction-bubble.show {
  opacity: 1;
}

/* Keyframes */
@keyframes doudou-bounce {
  0%, 100% { transform: scale(1) rotate(0deg); }
  25%       { transform: scale(1.15) rotate(-8deg); }
  55%       { transform: scale(1.2) rotate(0deg); }
  80%       { transform: scale(1.08) rotate(6deg); }
}
@keyframes doudou-shake {
  0%, 100% { transform: translateX(0) rotate(0deg); }
  20%      { transform: translateX(-7px) rotate(-4deg); }
  40%      { transform: translateX(7px) rotate(4deg); }
  60%      { transform: translateX(-4px) rotate(-2deg); }
  80%      { transform: translateX(4px) rotate(2deg); }
}
@keyframes doudou-pulse-anim {
  0%, 100% { transform: scale(1); }
  50%      { transform: scale(1.1); }
}

.doudou-correct   { animation: doudou-bounce 0.8s ease; }
.doudou-wrong     { animation: doudou-shake 0.8s ease; }
.doudou-transition { animation: doudou-pulse-anim 0.6s ease; }

@media (prefers-reduced-motion: reduce) {
  .doudou-correct, .doudou-wrong, .doudou-transition { animation: none; }
}

/* Self-assessment row inside answer-reveal */
.doudou-selfassess {
  display: flex;
  gap: 8px;
  margin-top: 12px;
  padding-top: 10px;
  border-top: 1px solid var(--line);
}
.doudou-got-right {
  flex: 1;
  background: var(--ok-bg);
  color: var(--ok-text);
  border: 1px solid var(--ok);
}
.doudou-got-right:hover {
  background: #c2e8c2;
}
.doudou-got-wrong {
  flex: 1;
  background: var(--warn-bg);
  color: var(--warn);
  border: 1px solid var(--warn);
}
.doudou-got-wrong:hover {
  background: #f5c8c5;
}