:root {
  --bg: #0b1020;
  --panel: #121a33;
  --panel-2: #0f1730;
  --text: #e6ebff;
  --muted: #9fb1ff;
  --primary: #5b86ff;
  --success: #33d69f;
  --warn: #ffb84d;
  --danger: #ff6b6b;
  --divider: #233056;
}

* { box-sizing: border-box; }
html, body { height: 100%; }
body {
  margin: 0;
  color: var(--text);
  background: radial-gradient(1000px 600px at 10% 0%, #0e1540 0%, #0a1022 60%, #070c18 100%);
  font-family: 'Noto Sans SC', ui-sans-serif, system-ui, -apple-system, Segoe UI, Roboto, Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "WenQuanYi Micro Hei", sans-serif;
}

.app-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: 16px 20px;
  border-bottom: 1px solid var(--divider);
  backdrop-filter: blur(6px);
  position: sticky; top: 0; z-index: 10;
  background: rgba(7,12,24,0.6);
}
.brand { display: flex; align-items: center; gap: 12px; }
.logo {
  width: 36px; height: 36px; border-radius: 10px;
  display: grid; place-items: center;
  background: linear-gradient(135deg, #6c8cff, #6fd6ff);
  color: #081224; font-weight: 800;
}
.title h1 { font-size: 18px; margin: 0; }
.title p { margin: 2px 0 0; font-size: 12px; color: var(--muted); }

.container { display: grid; grid-template-columns: 320px 1fr; gap: 20px; padding: 20px; }
.sidebar { display: flex; flex-direction: column; gap: 16px; }
.panel {
  background: linear-gradient(180deg, var(--panel) 0%, var(--panel-2) 100%);
  border: 1px solid var(--divider);
  border-radius: 14px; padding: 16px;
}
.author-panel { padding-bottom: 10px; }
.author-header { display: flex; gap: 12px; align-items: center; }
.author-avatar { width: 56px; height: 56px; border-radius: 12px; border: 1px solid var(--divider); background: #0d1635; object-fit: cover; }
.author-meta { display: flex; flex-direction: column; gap: 4px; }
.author-name { font-weight: 700; font-size: 16px; }
.author-wechat { font-size: 13px; color: var(--muted); }
.qr-wrap { margin-top: 12px; text-align: center; }
.author-qr { width: 100%; border-radius: 12px; border: 1px dashed #2b3a77; background: #0b1430; }
.qr-hint { margin-top: 6px; color: var(--muted); font-size: 12px; }
.panel h3 { margin: 0 0 10px; font-size: 16px; }
.checkbox { display: flex; align-items: center; gap: 8px; margin: 8px 0; }
.field { display: grid; grid-template-columns: 1fr auto; align-items: center; gap: 10px; margin: 10px 0; }
.field input[type="number"] { width: 90px; padding: 8px 10px; border-radius: 10px; border: 1px solid var(--divider); background: #0b1430; color: var(--text); }

.btn {
  border: 1px solid var(--divider);
  color: var(--text);
  background: #16224a;
  padding: 10px 14px; border-radius: 12px; cursor: pointer;
  transition: all .18s ease; font-weight: 600;
}
.btn:hover { transform: translateY(-1px); background: #1a2a5f; }
.btn.primary { background: linear-gradient(135deg, #5b86ff, #6fd6ff); color: #07122a; border: none; }
.btn.primary:hover { filter: brightness(1.05); }
.btn.small { padding: 8px 10px; font-size: 12px; }
.btn.success { background: #1d3a34; border-color: #2b7763; color: #8ff0cf; }
.btn.warn { background: #3a2e1d; border-color: #8c6a28; color: #ffd287; }
.btn.danger { background: #3a1f22; border-color: #8c323f; color: #ff97a3; }
.file-btn { position: relative; overflow: hidden; display: inline-block; }
.file-btn input[type="file"] { position: absolute; inset: 0; opacity: 0; cursor: pointer; }

.content { min-height: calc(100vh - 140px); }
.loading { padding: 60px; text-align: center; color: var(--muted); }

.study-view.hidden { display: none; }
.dashboard { display: none; }
.dashboard.active { display: block; }

.session-info { display: flex; gap: 16px; color: var(--muted); margin-bottom: 12px; }
.card {
  background: radial-gradient(600px 300px at 10% 0%, #182752 0%, #111a39 70%);
  border: 1px solid var(--divider);
  border-radius: 18px; padding: 26px; min-height: 220px;
  display: flex; flex-direction: column; gap: 14px;
}
.card .tag { align-self: flex-start; font-size: 12px; padding: 4px 8px; border-radius: 999px; background: #243160; color: #9fb1ff; border: 1px solid #2b3a77; margin-right: 6px; }
.card .tag.type { background: #2a3c2f; color: #8ff0cf; border-color: #295447; }
.card .front { font-size: 22px; line-height: 1.6; }
.card .divider { height: 1px; background: var(--divider); opacity: .6; }
.card .back { font-size: 16px; color: var(--muted); }
.card .sentence { font-size: 14px; color: #8fb0ff; opacity: .9; }
.back.hidden { visibility: hidden; }
.sentence.hidden { display: none; }
.controls { display: flex; align-items: center; gap: 8px; margin-top: 14px; }
.controls .spacer { flex: 1; }

/* 数据管理行内按钮对齐 */
.btn-row { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; }

.cards { display: grid; grid-template-columns: repeat(4, 1fr); gap: 12px; }
.kpi { background: linear-gradient(180deg, #111a36, #0f1730); border: 1px solid var(--divider); border-radius: 14px; padding: 16px; }
.kpi-value { font-size: 28px; font-weight: 800; }
.kpi-label { color: var(--muted); font-size: 12px; }

.charts { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 16px; }
.chart-card { background: linear-gradient(180deg, #111a36, #0f1730); border: 1px solid var(--divider); border-radius: 14px; padding: 16px; }

.footer { color: var(--muted); text-align: center; padding: 16px; border-top: 1px solid var(--divider); }

@media (max-width: 1080px) {
  .container { grid-template-columns: 1fr; }
  .cards { grid-template-columns: repeat(2, 1fr); }
  .charts { grid-template-columns: 1fr; }
}