:root {
  --bg: #0f1419;
  --card: #1a2332;
  --border: #2d3a4f;
  --text: #e8edf5;
  --muted: #8b9cb3;
  --primary: #4f8cff;
  --primary-hover: #3a7aef;
  --success: #34d399;
  --danger: #f87171;
  --radius: 12px;
}
* { box-sizing: border-box; margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", sans-serif;
  background: linear-gradient(135deg, #0f1419 0%, #1a1f35 100%);
  color: var(--text);
  min-height: 100vh;
  line-height: 1.6;
}
.header {
  display: flex; justify-content: space-between; align-items: center;
  padding: 16px 24px; border-bottom: 1px solid var(--border);
  background: rgba(26,35,50,.8); backdrop-filter: blur(8px);
  position: sticky; top: 0; z-index: 10;
}
.brand { font-size: 1.25rem; font-weight: 700; }
#app { max-width: 960px; margin: 0 auto; padding-bottom: 40px; }
.card {
  background: var(--card); border: 1px solid var(--border);
  border-radius: var(--radius); padding: 24px; margin: 16px;
}
.auth-card { max-width: 420px; margin: 60px auto; }
.hidden { display: none !important; }
.muted { color: var(--muted); font-size: .9rem; margin: 8px 0; }
input, select {
  width: 100%; padding: 12px 14px; margin: 8px 0;
  border: 1px solid var(--border); border-radius: 8px;
  background: #0f1419; color: var(--text); font-size: 1rem;
}
.btn {
  padding: 10px 18px; border: none; border-radius: 8px;
  cursor: pointer; font-size: .95rem; background: var(--border); color: var(--text);
  transition: .15s;
}
.btn:hover { opacity: .9; }
.btn.primary { background: var(--primary); color: #fff; }
.btn.primary:hover { background: var(--primary-hover); }
.btn.ghost { background: transparent; border: 1px solid var(--border); }
.btn.success { background: var(--success); color: #0f1419; }
.tabs { display: flex; gap: 8px; margin: 16px 0; }
.tab {
  flex: 1; padding: 8px; border: 1px solid var(--border);
  background: transparent; color: var(--muted); border-radius: 8px; cursor: pointer;
}
.tab.active { background: var(--primary); color: #fff; border-color: var(--primary); }
.error { color: var(--danger); margin-top: 8px; font-size: .9rem; }
.nav {
  display: flex; gap: 4px; padding: 12px 16px 0; overflow-x: auto;
}
.nav-btn {
  padding: 8px 14px; border: 1px solid var(--border); background: transparent;
  color: var(--muted); border-radius: 20px; cursor: pointer; white-space: nowrap;
}
.nav-btn.active { background: var(--primary); color: #fff; border-color: var(--primary); }
.grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(180px, 1fr)); gap: 0; }
.stat { text-align: center; }
.stat-label { color: var(--muted); font-size: .85rem; }
.stat-value { font-size: 1.5rem; font-weight: 700; margin-top: 4px; }
.actions { display: flex; flex-wrap: wrap; gap: 10px; margin-top: 12px; }
.row-between { display: flex; justify-content: space-between; align-items: center; gap: 12px; }
.plan-item {
  border: 1px solid var(--border); border-radius: 10px;
  padding: 16px; margin: 12px 0; background: rgba(15,20,25,.5);
}
.plan-item.done { border-color: var(--success); opacity: .75; }
.plan-item h4 { margin-bottom: 6px; }
.tag {
  display: inline-block; padding: 2px 8px; border-radius: 4px;
  font-size: .75rem; background: var(--border); margin-right: 6px;
}
.exercise-card {
  border: 1px solid var(--border); border-radius: 10px;
  padding: 16px; margin: 12px 0;
}
.exercise-card input { margin-top: 8px; }
.feedback { margin-top: 10px; padding: 10px; border-radius: 8px; font-size: .9rem; }
.feedback.ok { background: rgba(52,211,153,.15); color: var(--success); }
.feedback.bad { background: rgba(248,113,113,.15); color: var(--danger); }
.badge {
  background: var(--primary); color: #fff; padding: 4px 10px;
  border-radius: 20px; font-size: .85rem; margin-right: 12px;
}
#user-bar { display: flex; align-items: center; gap: 8px; }
.progress-bar {
  height: 6px; background: var(--border); border-radius: 3px; margin-top: 8px; overflow: hidden;
}
.progress-bar div { height: 100%; background: var(--primary); transition: width .3s; }
.material-row {
  padding: 10px 0; border-bottom: 1px solid var(--border);
  display: flex; justify-content: space-between; font-size: .9rem;
}
.hint { font-size: .85rem; color: var(--muted); padding: 8px 16px; }
.w { cursor: help; border-bottom: 1px dotted rgba(79,140,255,.35); transition: .12s; }
.w:hover { color: var(--primary); border-bottom-color: var(--primary); background: rgba(79,140,255,.08); border-radius: 2px; }
.interactive-text { line-height: 1.8; margin: 10px 0; user-select: text; }
.passage { background: rgba(0,0,0,.25); padding: 14px; border-radius: 8px; margin: 10px 0; font-size: .95rem; }
.section-tags { display: flex; flex-wrap: wrap; gap: 8px; margin: 12px 0; }
.section-tag { cursor: pointer; transition: .15s; }
.section-tag:hover { background: var(--primary); color: #fff; }
.exam-tag { background: rgba(79,140,255,.25); color: var(--primary); }

/* 悬停翻译气泡 */
.word-tooltip, .selection-popup {
  position: fixed; z-index: 200;
  background: var(--card); border: 1px solid var(--border);
  border-radius: 10px; padding: 12px 14px;
  box-shadow: 0 8px 32px rgba(0,0,0,.45);
  min-width: 180px; max-width: 320px;
  pointer-events: auto;
  animation: tipIn .15s ease-out;
}
@keyframes tipIn {
  from { opacity: 0; transform: translateY(4px); }
  to { opacity: 1; transform: translateY(0); }
}
.tip-word { font-size: 1.15rem; font-weight: 700; color: var(--text); }
.tip-phonetic { font-size: .85rem; color: var(--muted); margin-top: 2px; font-family: "Lucida Sans Unicode", sans-serif; }
.tip-trans { font-size: .95rem; margin: 8px 0 6px; color: var(--success); line-height: 1.5; }
.tip-actions { display: flex; gap: 6px; margin-top: 4px; }
.tip-btn {
  padding: 6px 12px; border: 1px solid var(--border); border-radius: 6px;
  background: rgba(15,20,25,.6); color: var(--text); cursor: pointer; font-size: .9rem;
  transition: .12s;
}
.tip-btn:hover { background: var(--primary); border-color: var(--primary); }
.tip-btn.tip-save.saved { background: rgba(52,211,153,.2); border-color: var(--success); color: var(--success); }
.tip-speech { margin-top: 8px; padding: 8px; border-radius: 6px; font-size: .85rem; line-height: 1.4; }
.tip-speech.ok { background: rgba(52,211,153,.15); color: var(--success); }
.tip-speech.bad { background: rgba(248,113,113,.15); color: var(--danger); }

.speech-result { margin-top: 12px; padding: 10px; border-radius: 8px; font-size: .9rem; }
.speech-result.ok { background: rgba(52,211,153,.15); color: var(--success); }
.speech-result.bad { background: rgba(248,113,113,.15); color: var(--danger); }
.vocab-card {
  border: 1px solid var(--border); border-radius: 8px; padding: 12px; margin: 8px 0;
}
.progress-tag { background: rgba(79,140,255,.2); color: var(--primary); }
.done-tag { background: rgba(52,211,153,.2); color: var(--success); }
textarea { width: 100%; padding: 10px; margin: 8px 0; border: 1px solid var(--border); border-radius: 8px; background: #0f1419; color: var(--text); font-family: inherit; resize: vertical; }

.code-row { display: flex; gap: 8px; }
.code-row input { flex: 1; margin: 8px 0; }
.code-row .btn { margin: 8px 0; white-space: nowrap; }
.wechat-box { text-align: center; padding: 12px 0; }
.auth-tabs { flex-wrap: wrap; }

.module-card {
  border: 1px solid var(--border); border-radius: 10px;
  padding: 16px; margin: 14px 0; background: rgba(15,20,25,.4);
}
.module-card h4 { margin-bottom: 6px; color: var(--primary); }
.node-card {
  border-left: 3px solid var(--border); padding: 10px 12px; margin: 10px 0;
  background: rgba(0,0,0,.15); border-radius: 0 8px 8px 0;
}
.node-summary { font-size: .9rem; color: var(--success); margin: 6px 0; }
.exam-points { font-size: .85rem; color: var(--muted); margin-top: 6px; }
.video-link { display: inline-block; margin-top: 8px; color: var(--primary); font-size: .9rem; text-decoration: none; }
.video-link:hover { text-decoration: underline; }