:root {
  --bg: #0f1221;
  --bg-card: #191c33;
  --bg-elev: #222647;
  --text: #e8ecf7;
  --text-mute: #9aa3c7;
  --accent: #7c6cff;
  --accent-2: #4de3c1;
  --danger: #ff6b81;
  --warn: #ffb84d;
  --ok: #4de3c1;
  --border: #2a2f55;
  --radius: 14px;
  --shadow: 0 10px 30px rgba(0, 0, 0, 0.35);
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: radial-gradient(1200px 600px at 10% -10%, #242a52 0%, transparent 60%),
              radial-gradient(1000px 500px at 100% 0%, #2a1e4a 0%, transparent 55%),
              var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
               "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  min-height: 100vh;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 24px;
  border-bottom: 1px solid var(--border);
  gap: 16px;
  flex-wrap: wrap;
}

.brand {
  display: flex;
  align-items: center;
  gap: 12px;
}

.logo {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  color: #0f1221;
  font-size: 20px;
}

.brand h1 { margin: 0; font-size: 18px; letter-spacing: 0.5px; }
.brand .sub { margin: 2px 0 0; color: var(--text-mute); font-size: 12px; }

.tabs {
  display: flex;
  gap: 6px;
  flex-wrap: wrap;
}

.tab {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text-mute);
  padding: 8px 14px;
  border-radius: 999px;
  cursor: pointer;
  font-size: 13px;
  transition: all 0.15s ease;
}
.tab:hover { color: var(--text); border-color: #3a4075; }
.tab.active {
  background: var(--accent);
  color: #fff;
  border-color: var(--accent);
}

main {
  padding: 28px 24px 80px;
  max-width: 920px;
  margin: 0 auto;
}

.view { animation: fade 0.2s ease; }
.hidden { display: none !important; }

@keyframes fade {
  from { opacity: 0; transform: translateY(4px); }
  to   { opacity: 1; transform: translateY(0); }
}

/* ===== Learn ===== */
.progress-bar {
  position: relative;
  width: 100%;
  height: 10px;
  background: var(--bg-card);
  border-radius: 999px;
  overflow: hidden;
  margin-bottom: 18px;
}
.progress-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  transition: width 0.3s ease;
}
.progress-text {
  position: absolute;
  right: 12px;
  top: -22px;
  font-size: 12px;
  color: var(--text-mute);
}

.card {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 40px 28px;
  box-shadow: var(--shadow);
  min-height: 360px;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  text-align: center;
  cursor: pointer;
  user-select: none;
}

.card-front, .card-back { width: 100%; }

.word {
  font-size: 44px;
  font-weight: 700;
  letter-spacing: 1px;
  margin-bottom: 8px;
}
.phonetic {
  color: var(--text-mute);
  font-size: 18px;
  margin-bottom: 24px;
  font-family: "Courier New", monospace;
}
.pos {
  display: inline-block;
  padding: 3px 10px;
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--accent-2);
  font-size: 13px;
  margin-bottom: 12px;
}
.meaning {
  font-size: 20px;
  color: var(--text);
  margin-bottom: 18px;
  line-height: 1.5;
}
.example {
  color: var(--text);
  font-style: italic;
  margin-bottom: 4px;
  padding: 0 10px;
}
.example-zh {
  color: var(--text-mute);
  font-size: 14px;
  margin-bottom: 22px;
  padding: 0 10px;
}

.reveal-btn {
  margin: 0 auto 8px;
  background: transparent;
  border: 1px solid var(--accent);
  color: var(--accent);
  padding: 10px 24px;
  border-radius: 999px;
  cursor: pointer;
  font-size: 14px;
  transition: all 0.15s;
}
.reveal-btn:hover { background: var(--accent); color: #fff; }

.hint { color: var(--text-mute); font-size: 12px; margin-top: 14px; }

.rate-row {
  display: flex;
  gap: 10px;
  justify-content: center;
  margin-top: 12px;
  flex-wrap: wrap;
}
.rate {
  padding: 10px 20px;
  border: none;
  border-radius: 10px;
  color: #fff;
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
  min-width: 100px;
  transition: transform 0.1s ease;
}
.rate:hover { transform: translateY(-1px); }
.rate-hard { background: var(--danger); }
.rate-mid  { background: var(--warn); }
.rate-easy { background: var(--ok); color: #0f1221; }

.done-panel {
  text-align: center;
  padding: 40px 20px;
  background: var(--bg-card);
  border-radius: var(--radius);
  border: 1px solid var(--border);
}
.done-panel h2 { margin: 0 0 12px; }
.done-panel p  { color: var(--text-mute); }

/* ===== Story ===== */
.story-wrap {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}
.story-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
  flex-wrap: wrap;
  gap: 8px;
}
.story-header h2 { margin: 0; }
.story-actions { display: flex; gap: 8px; }

.story-body { line-height: 1.9; font-size: 15px; }
.story-en {
  padding: 16px;
  background: var(--bg-elev);
  border-radius: 10px;
  margin-bottom: 14px;
}
.story-zh {
  padding: 16px;
  background: rgba(124, 108, 255, 0.08);
  border-radius: 10px;
  color: var(--text-mute);
}
.story-title {
  font-weight: 700;
  font-size: 18px;
  margin-bottom: 10px;
  color: var(--accent-2);
}
.hl {
  color: var(--accent-2);
  font-weight: 600;
  border-bottom: 1px dashed var(--accent-2);
}
.placeholder { color: var(--text-mute); }

.story-loading {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text-mute);
  padding: 20px 0;
}
.spin {
  width: 18px;
  height: 18px;
  border: 2px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin 0.8s linear infinite;
}
@keyframes spin { to { transform: rotate(360deg); } }

/* ===== Review & Stats ===== */
.review-wrap, .stats-wrap, .settings-wrap {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  box-shadow: var(--shadow);
}

.muted { color: var(--text-mute); }

.stat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: 12px;
  margin: 14px 0 24px;
}
.stat-card {
  background: var(--bg-elev);
  border-radius: 10px;
  padding: 14px;
  border: 1px solid var(--border);
}
.stat-num {
  font-size: 28px;
  font-weight: 700;
  color: var(--accent-2);
}
.stat-label { color: var(--text-mute); font-size: 13px; margin-top: 4px; }

.heat {
  display: grid;
  grid-template-columns: repeat(14, 1fr);
  gap: 6px;
  margin-bottom: 24px;
}
.heat-cell {
  aspect-ratio: 1 / 1;
  border-radius: 4px;
  background: var(--bg-elev);
}
.heat-cell.lv1 { background: rgba(77, 227, 193, 0.25); }
.heat-cell.lv2 { background: rgba(77, 227, 193, 0.55); }
.heat-cell.lv3 { background: rgba(77, 227, 193, 0.85); }

.known-list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
}
.known-list .pill {
  padding: 4px 10px;
  background: var(--bg-elev);
  border-radius: 999px;
  font-size: 13px;
  border: 1px solid var(--border);
}

/* ===== Settings ===== */
.field { margin-bottom: 14px; }
.field label {
  display: block;
  font-size: 13px;
  color: var(--text-mute);
  margin-bottom: 6px;
}
.field input, .field select {
  width: 100%;
  padding: 10px 12px;
  background: var(--bg-elev);
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 8px;
  font-size: 14px;
  outline: none;
}
.field input:focus, .field select:focus { border-color: var(--accent); }

.actions { display: flex; gap: 10px; flex-wrap: wrap; margin-top: 20px; }
.primary, .ghost, .danger {
  padding: 10px 20px;
  border-radius: 10px;
  border: none;
  cursor: pointer;
  font-size: 14px;
  font-weight: 600;
}
.primary { background: var(--accent); color: #fff; }
.primary:hover { filter: brightness(1.1); }
.ghost {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--border);
}
.ghost:hover { border-color: var(--accent); }
.danger { background: var(--danger); color: #fff; }

.save-tip { color: var(--ok); font-size: 13px; margin-top: 10px; }

/* ===== Footer ===== */
.foot {
  text-align: center;
  padding: 24px 16px;
  color: var(--text-mute);
  font-size: 12px;
}
.foot .dot { margin: 0 6px; opacity: 0.5; }

/* ===== Mobile ===== */
@media (max-width: 640px) {
  .topbar { padding: 12px 14px; }
  .tabs { width: 100%; overflow-x: auto; flex-wrap: nowrap; }
  .tab { flex-shrink: 0; }
  main { padding: 20px 14px 60px; }
  .word { font-size: 34px; }
  .card { padding: 28px 18px; min-height: 320px; }
  .rate { min-width: 80px; padding: 10px 12px; }
}


/* ===== Cloud Sync ===== */
.cloud-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: 999px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  color: var(--text-mute);
  cursor: pointer;
  font-size: 12px;
  transition: all 0.15s;
}
.cloud-chip:hover { border-color: var(--accent); color: var(--text); }
.cloud-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #555;
}
.cloud-chip.ok .cloud-dot { background: var(--ok); box-shadow: 0 0 6px var(--ok); }
.cloud-chip.syncing .cloud-dot { background: var(--warn); animation: pulse 1s infinite; }
.cloud-chip.error .cloud-dot { background: var(--danger); }

@keyframes pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.4; }
}

hr.sep {
  border: none;
  border-top: 1px solid var(--border);
  margin: 26px 0 18px;
}

.auth-panel {
  background: var(--bg-elev);
  padding: 16px;
  border-radius: 10px;
  border: 1px solid var(--border);
}