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

:root {
  --primary: #4A90D9;
  --primary-light: #E8F0FE;
  --primary-dark: #3570B0;
  --success: #5CB85C;
  --warning: #F0AD4E;
  --danger: #D9534F;
  --bg: #F5F7FA;
  --card: #FFFFFF;
  --text: #333333;
  --text-secondary: #888888;
  --border: #E8E8E8;
  --radius: 12px;
  --shadow: 0 2px 8px rgba(0,0,0,0.06);
  --nav-height: 56px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 14px;
  line-height: 1.5;
  max-width: 480px;
  margin: 0 auto;
  min-height: 100vh;
  position: relative;
  overflow-x: hidden;
}

.page { padding: 16px 16px calc(var(--nav-height) + 20px); min-height: 100vh; }
.page-no-nav { padding: 16px 16px 40px; min-height: 100vh; }

.page-header { display:flex; align-items:center; justify-content:space-between; margin-bottom:20px; }
.page-header h1 { font-size:20px; font-weight:700; }
.page-header .header-right { display:flex; align-items:center; gap:12px; }
.page-header .header-left { display:flex; align-items:center; gap:8px; }

.btn-back { background:none; border:none; font-size:18px; cursor:pointer; padding:4px 8px; color:var(--text); text-decoration:none; }
.btn-icon { background:none; border:none; font-size:22px; cursor:pointer; padding:4px; color:var(--text); text-decoration:none; }

.card { background:var(--card); border-radius:var(--radius); box-shadow:var(--shadow); padding:16px; margin-bottom:12px; }

.card-row { background:var(--card); border-radius:var(--radius); box-shadow:var(--shadow); padding:14px 16px; margin-bottom:10px; display:flex; align-items:center; justify-content:space-between; cursor:pointer; transition:transform 0.1s; }
.card-row:active { transform:scale(0.98); }
.card-row .row-left { display:flex; align-items:center; gap:12px; }
.card-row .row-icon { font-size:20px; width:36px; height:36px; display:flex; align-items:center; justify-content:center; border-radius:8px; flex-shrink:0; }
.card-row .row-arrow { color:var(--text-secondary); font-size:16px; }
.card-title { font-size:16px; font-weight:600; margin-bottom:8px; }

.btn { display:inline-flex; align-items:center; justify-content:center; padding:10px 24px; border:none; border-radius:8px; font-size:15px; font-weight:600; cursor:pointer; transition:background 0.15s; text-decoration:none; }
.btn-primary { background:var(--primary); color:#fff; width:100%; }
.btn-primary:active { background:var(--primary-dark); }
.btn-primary:disabled { background:var(--border); color:var(--text-secondary); cursor:default; }
.btn-outline { background:transparent; border:1.5px solid var(--primary); color:var(--primary); }
.btn-success { background:var(--success); color:#fff; }
.btn-warning { background:var(--warning); color:#fff; }
.btn-danger { background:var(--danger); color:#fff; }

.bottom-nav { position:fixed; bottom:0; left:50%; transform:translateX(-50%); width:100%; max-width:480px; height:var(--nav-height); background:var(--card); display:flex; align-items:center; justify-content:space-around; box-shadow:0 -2px 8px rgba(0,0,0,0.05); z-index:100; padding-bottom:env(safe-area-inset-bottom,0); }
.nav-item { display:flex; flex-direction:column; align-items:center; gap:2px; padding:4px 12px; text-decoration:none; color:var(--text-secondary); font-size:11px; transition:color 0.15s; cursor:pointer; }
.nav-item .nav-icon { font-size:22px; line-height:1; }
.nav-item.active { color:var(--primary); }

.progress-bar { height:8px; background:var(--border); border-radius:4px; overflow:hidden; }
.progress-bar .progress-fill { height:100%; background:linear-gradient(90deg,var(--primary),var(--success)); border-radius:4px; transition:width 0.3s; }

.stat-grid { display:flex; gap:10px; margin-bottom:16px; }
.stat-grid .stat-card { flex:1; background:var(--card); border-radius:var(--radius); box-shadow:var(--shadow); padding:14px 8px; text-align:center; }
.stat-grid .stat-number { font-size:22px; font-weight:700; color:var(--primary); }
.stat-grid .stat-label { font-size:12px; color:var(--text-secondary); margin-top:2px; }

.section-title { font-size:15px; font-weight:600; margin-bottom:10px; margin-top:6px; }
.steps { display:flex; justify-content:center; gap:8px; margin-bottom:24px; }
.step-dot { width:10px; height:10px; border-radius:50%; background:var(--border); transition:background 0.3s; }
.step-dot.active { background:var(--primary); }

.word-card { background:var(--card); border-radius:var(--radius); box-shadow:var(--shadow); padding:20px; margin-bottom:12px; text-align:center; }
.word-card .word { font-size:24px; font-weight:700; }
.word-card .phonetic { font-size:14px; color:var(--text-secondary); margin-top:4px; }
.word-card .meaning { font-size:16px; color:var(--text); margin-top:10px; }

.choices { display:flex; flex-direction:column; gap:10px; margin-top:16px; }
.choice-btn { display:block; width:100%; padding:12px 16px; border:1.5px solid var(--border); border-radius:8px; background:var(--card); font-size:14px; text-align:left; cursor:pointer; transition:all 0.15s; }
.choice-btn:active { background:var(--primary-light); border-color:var(--primary); }
.choice-btn.correct { background:#DFF0D8; border-color:var(--success); color:#3C763D; }
.choice-btn.wrong { background:#F2DEDE; border-color:var(--danger); color:#A94442; }
.choice-btn:disabled { cursor:default; }

.review-btns { display:flex; gap:10px; margin-top:20px; }
.review-btn { flex:1; padding:12px 8px; border:none; border-radius:8px; font-size:14px; font-weight:600; cursor:pointer; transition:transform 0.1s; }
.review-btn:active { transform:scale(0.95); }
.review-btn.know { background:#DFF0D8; color:#3C763D; }
.review-btn.unsure { background:#FCF8E3; color:#8A6D3B; }
.review-btn.forget { background:#F2DEDE; color:#A94442; }

.tag { display:inline-block; padding:2px 8px; border-radius:4px; font-size:12px; font-weight:500; }
.tag-removing { background:#FCF8E3; color:#8A6D3B; }
.tag-removed { background:#DFF0D8; color:#3C763D; }
.tag-error { background:#F2DEDE; color:#A94442; }

.group-divider { display:flex; align-items:center; gap:8px; margin:16px 0 10px; font-size:14px; font-weight:600; color:var(--text-secondary); }
.group-divider::after { content:''; flex:1; height:1px; background:var(--border); }

.filter-tabs { display:flex; gap:8px; margin-bottom:14px; overflow-x:auto; -webkit-overflow-scrolling:touch; }
.filter-tab { padding:6px 16px; border:1px solid var(--border); border-radius:20px; font-size:13px; cursor:pointer; background:var(--card); white-space:nowrap; transition:all 0.15s; }
.filter-tab.active { background:var(--primary); color:#fff; border-color:var(--primary); }
.filter-tabs::-webkit-scrollbar { display:none; }

@media (min-width: 481px) {
  body { border-left:1px solid var(--border); border-right:1px solid var(--border); box-shadow:0 0 20px rgba(0,0,0,0.05); }
}

.fade-in { animation:fadeIn 0.25s ease-in; }
@keyframes fadeIn { from { opacity:0; transform:translateY(8px); } to { opacity:1; transform:translateY(0); } }

.text-center { text-align:center; }
.mt-8 { margin-top:8px; }
.mt-16 { margin-top:16px; }
.mt-24 { margin-top:24px; }
.mb-8 { margin-bottom:8px; }
.mb-16 { margin-bottom:16px; }

/* ===== Cultivation Realm Badge ===== */
.realm-badge {
  display:inline-flex; align-items:center; gap:6px;
  padding:6px 14px; border-radius:20px;
  font-size:14px; font-weight:700;
  box-shadow:0 2px 8px rgba(0,0,0,0.1);
}

.realm-badge .realm-icon { font-size:18px; }

/* Cultivation Progress */
.cultivation-bar { height:8px; background:var(--border); border-radius:4px; overflow:hidden; }
.cultivation-bar .cultivation-fill { height:100%; border-radius:4px; transition:width 0.4s; }

/* ===== Sect Badge ===== */
.sect-tag {
  display:inline-block; padding:3px 12px; border-radius:12px;
  font-size:12px; font-weight:600;
  background:linear-gradient(135deg,#E8F5E9,#C8E6C9); color:#2E7D32;
}

/* ===== Tribulation Effect ===== */
.tribulation-overlay {
  position:fixed; top:0; left:0; width:100%; height:100%;
  background:rgba(255,215,0,0.15); z-index:9999;
  display:flex; align-items:center; justify-content:center;
  animation:tribFlash 0.5s ease-out;
}

@keyframes tribFlash {
  0% { background:rgba(255,215,0,0.6); }
  100% { background:rgba(255,215,0,0.15); }
}

.tribulation-text {
  font-size:28px; font-weight:700; color:#FF8F00;
  text-shadow:0 0 20px rgba(255,215,0,0.5);
  animation:tribScale 0.6s ease-out;
}

@keyframes tribScale {
  0% { transform:scale(0.3); opacity:0; }
  50% { transform:scale(1.2); }
  100% { transform:scale(1); opacity:1; }
}

.trib-particle {
  position:fixed; width:8px; height:8px; border-radius:50%;
  background:#FFD600; z-index:10000;
  animation:particleFly 1.5s ease-out forwards;
}

@keyframes particleFly {
  0% { transform:translate(0,0) scale(1); opacity:1; }
  100% { transform:translate(var(--tx),var(--ty)) scale(0); opacity:0; }
}

/* ===== Textbook selector ===== */
.publisher-opt {
  text-align:center; padding:20px 12px; cursor:pointer;
  border:2px solid var(--border); border-radius:var(--radius);
  transition:all 0.15s; background:var(--card);
}
.publisher-opt:active { transform:scale(0.97); }
.publisher-opt.selected { border-color:var(--primary); background:var(--primary-light); }

.grade-opt {
  text-align:center; padding:14px 12px; cursor:pointer;
  border:1.5px solid var(--border); border-radius:8px;
  transition:all 0.1s; background:var(--card); font-weight:500;
}
.grade-opt:active { transform:scale(0.97); }
.grade-opt.selected { border-color:var(--primary); background:var(--primary-light); color:var(--primary); font-weight:600; }

/* ===== Tribulation question progress ===== */
.q-progress { display:flex; gap:4px; margin-bottom:16px; }
.q-dot { width:14px; height:14px; border-radius:50%; background:var(--border); flex-shrink:0; transition:background 0.2s; }
.q-dot.done { background:var(--success); }
.q-dot.current { background:var(--primary); box-shadow:0 0 0 3px var(--primary-light); }
.q-dot.wrong { background:var(--danger); }

/* ===== Toggle Switch ===== */
.toggle-switch {
  position: relative; width: 44px; height: 24px;
  background: var(--border); border-radius: 12px;
  cursor: pointer; transition: background 0.2s; flex-shrink: 0;
}
.toggle-switch.on { background: var(--primary); }
.toggle-switch .knob {
  position: absolute; top: 2px; left: 2px;
  width: 20px; height: 20px; background: #fff;
  border-radius: 50%; transition: left 0.2s;
  box-shadow: 0 1px 3px rgba(0,0,0,0.15);
}
.toggle-switch.on .knob { left: 22px; }

/* ===== Input ===== */
.text-input { width:100%; padding:12px; border:1.5px solid var(--border); border-radius:8px; font-size:16px; text-align:center; letter-spacing:2px; outline:none; transition:border-color 0.15s; }
.text-input:focus { border-color:var(--primary); }
.text-input.correct { border-color:var(--success); background:#DFF0D8; }
.text-input.wrong { border-color:var(--danger); background:#F2DEDE; }