:root {
  --bg: #f4f7fb;
  --surface: #ffffff;
  --surface-alt: #f8fafc;
  --border: #e2e8f0;
  --text: #0f172a;
  --text-muted: #475569;
  --primary: #0f766e;
  --primary-light: #ccfbf1;
  --accent: #2563eb;
  --accent-light: #dbeafe;
  --warn: #d97706;
  --warn-light: #fef3c7;
  --danger: #dc2626;
  --danger-light: #fee2e2;
  --ok: #16a34a;
  --ok-light: #dcfce7;
  --radius: 12px;
  --shadow: 0 2px 10px rgba(15, 23, 42, 0.05);
}

* { box-sizing: border-box; }

body {
  margin: 0;
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC", "Microsoft YaHei", "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.55;
}

.topbar {
  background: #0f172a;
  color: #f8fafc;
  padding: 12px 24px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  position: sticky;
  top: 0;
  z-index: 40;
  box-shadow: 0 2px 12px rgba(0, 0, 0, 0.15);
}

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

.brand-badge {
  background: linear-gradient(135deg, #14b8a6, #2563eb);
  color: #fff;
  font-weight: 700;
  padding: 6px 11px;
  border-radius: 8px;
  font-size: 13px;
  letter-spacing: 0.4px;
}

.brand h1 {
  margin: 0;
  font-size: 17px;
  font-weight: 600;
}

.brand-sub {
  font-size: 12px;
  color: #94a3b8;
}

.topbar-controls {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
}

select, input, textarea {
  font-family: inherit;
  font-size: 13px;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 7px 10px;
  background: #fff;
  color: var(--text);
}

.topbar select {
  background: #1e293b;
  color: #f8fafc;
  border-color: #334155;
  max-width: 300px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  border: 1px solid var(--border);
  background: #fff;
  color: var(--text);
  border-radius: 8px;
  padding: 7px 13px;
  font-size: 13px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s ease;
}

.btn:hover { background: #f1f5f9; }
.btn-primary { background: var(--primary); color: #fff; border-color: var(--primary); }
.btn-primary:hover { background: #0d625c; }
.btn-accent { background: var(--accent); color: #fff; border-color: var(--accent); }
.btn-accent:hover { background: #1d4ed8; }
.btn-danger { background: var(--danger); color: #fff; border-color: var(--danger); }
.btn-warn { background: var(--warn); color: #fff; border-color: var(--warn); }
.btn-sm { padding: 4px 9px; font-size: 12px; }

.nav-tabs {
  background: var(--surface);
  border-bottom: 1px solid var(--border);
  padding: 0 24px;
  display: flex;
  gap: 6px;
  overflow-x: auto;
}

.tab-btn {
  border: none;
  background: transparent;
  padding: 13px 16px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-muted);
  cursor: pointer;
  border-bottom: 3px solid transparent;
  white-space: nowrap;
}

.tab-btn.active {
  color: var(--primary);
  border-bottom-color: var(--primary);
  font-weight: 600;
}

.container {
  max-width: 1440px;
  margin: 0 auto;
  padding: 18px 24px 48px;
}

.tab-panel { display: none; }
.tab-panel.active { display: block; }

.session-banner {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 12px 16px;
  margin-bottom: 16px;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  box-shadow: var(--shadow);
}

.pill {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 3px 10px;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 600;
}

.pill-ok { background: var(--ok-light); color: #15803d; }
.pill-warn { background: var(--warn-light); color: #b45309; }
.pill-danger { background: var(--danger-light); color: #b91c1c; }
.pill-info { background: var(--accent-light); color: #1d4ed8; }
.pill-teal { background: var(--primary-light); color: #0f766e; }

.grid-3 {
  display: grid;
  grid-template-columns: 320px 1fr 370px;
  gap: 16px;
  align-items: start;
}

.grid-2 {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  align-items: start;
}

.grid-4 {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 12px;
}

@media (max-width: 1180px) {
  .grid-3 { grid-template-columns: 1fr; }
  .grid-2 { grid-template-columns: 1fr; }
  .grid-4 { grid-template-columns: repeat(2, 1fr); }
}

.card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 16px;
  box-shadow: var(--shadow);
  margin-bottom: 16px;
}

.card-title {
  margin: 0 0 12px;
  font-size: 15px;
  font-weight: 600;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
}

.kpi-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 10px;
}

.kpi-box {
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 10px 12px;
}

.kpi-label { font-size: 12px; color: var(--text-muted); }
.kpi-val { font-size: 20px; font-weight: 700; margin-top: 2px; }

.constraint-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 7px 10px;
  border-radius: 8px;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  margin-bottom: 6px;
  font-size: 12.5px;
}

.constraint-item.fail {
  background: #fef2f2;
  border-color: #fecaca;
}

.timeline-feed {
  max-height: 410px;
  overflow-y: auto;
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding-right: 4px;
}

.event-row {
  padding: 10px 12px;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--surface-alt);
  font-size: 13px;
}

.event-row.teacher { border-left: 4px solid var(--primary); }
.event-row.student { border-left: 4px solid var(--accent); background: #f8fbff; }
.event-row.silence { border-left: 4px solid var(--warn); background: #fffbeb; }

.event-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 6px;
  font-size: 11.5px;
  color: var(--text-muted);
  margin-bottom: 4px;
}

.alert-card {
  border: 1px solid #fed7aa;
  background: #fffaf0;
  border-left: 4px solid var(--warn);
  border-radius: 10px;
  padding: 12px;
  margin-bottom: 10px;
}

.alert-card.high {
  border-color: #fecaca;
  background: #fef2f2;
  border-left-color: var(--danger);
}

.alert-card h4 {
  margin: 0 0 6px;
  font-size: 13.5px;
}

.script-quote {
  background: #fff;
  border: 1px dashed #94a3b8;
  padding: 8px 10px;
  border-radius: 8px;
  font-size: 12.5px;
  margin: 8px 0;
  color: #1e293b;
}

.tool-chips {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 8px;
}

.meter-bar {
  height: 8px;
  background: #e2e8f0;
  border-radius: 999px;
  overflow: hidden;
  margin-top: 6px;
}

.meter-fill {
  height: 100%;
  background: linear-gradient(90deg, #14b8a6, #2563eb);
  width: 0%;
  transition: width 0.1s linear;
}

.four-he-stack {
  display: flex;
  height: 22px;
  border-radius: 8px;
  overflow: hidden;
  background: #e2e8f0;
  margin: 8px 0;
}

.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(15, 23, 42, 0.55);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 60;
  padding: 16px;
}

.modal-backdrop.open { display: flex; }

.modal {
  background: #fff;
  border-radius: 14px;
  max-width: 680px;
  width: 100%;
  max-height: 88vh;
  overflow-y: auto;
  padding: 20px;
  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.25);
}

.chat-box {
  height: 360px;
  overflow-y: auto;
  background: var(--surface-alt);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 10px;
}

.chat-msg {
  max-width: 88%;
  padding: 10px 12px;
  border-radius: 10px;
  font-size: 13px;
  white-space: pre-wrap;
}

.chat-msg.user {
  align-self: flex-end;
  background: var(--primary);
  color: #fff;
}

.chat-msg.assistant {
  align-self: flex-start;
  background: #fff;
  border: 1px solid var(--border);
}

.unobserved-box {
  background: #f1f5f9;
  border: 1px dashed #64748b;
  border-radius: 10px;
  padding: 12px;
  font-size: 13px;
  color: #334155;
}

.video-preview {
  width: 100%;
  max-height: 170px;
  background: #0f172a;
  border-radius: 8px;
  object-fit: cover;
  margin-top: 8px;
  display: none;
}

.svg-box {
  width: 100%;
  display: flex;
  justify-content: center;
}

.muted { color: var(--text-muted); font-size: 12.5px; }

/* ==================== AI算力切换中心 & 网络课堂视频流 ==================== */
.engine-pill-btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 11px;
  border-radius: 999px;
  border: 1px solid #cbd5e1;
  background: #f8fafc;
  color: #0f172a;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
}
.engine-pill-btn:hover { border-color: var(--primary); background: #f0fdfa; }

.stream-panel {
  margin-top: 12px;
  border-top: 1px solid var(--border);
  padding-top: 10px;
}

.stream-video-box {
  width: 100%;
  max-height: 220px;
  border-radius: 8px;
  background: #0f172a;
  margin-top: 8px;
  display: none;
}

.stream-video-box.active { display: block; }

.stream-meta-card {
  margin-top: 8px;
  padding: 8px 10px;
  border-radius: 8px;
  background: #f8fafc;
  border: 1px solid var(--border);
  font-size: 12px;
  line-height: 1.5;
}

.chip-row {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 8px 0;
}

.model-chip {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border-radius: 999px;
  border: 1px solid var(--border);
  background: #fff;
  font-size: 12px;
  cursor: pointer;
  transition: all 0.15s ease;
}
.model-chip:hover { border-color: var(--primary); background: #f0fdfa; }
.model-chip.active {
  background: #0f766e;
  color: #fff;
  border-color: #0f766e;
  font-weight: 600;
}

.provider-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 12px;
  margin-top: 10px;
}
@media (max-width: 1024px) {
  .provider-grid { grid-template-columns: 1fr; }
}

.provider-card {
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px;
  background: #fafcff;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.provider-card.selected {
  border-color: var(--primary);
  box-shadow: 0 0 0 2px rgba(15, 118, 110, 0.12);
  background: #f0fdfa;
}

.form-label {
  display: flex;
  flex-direction: column;
  gap: 4px;
  font-size: 12px;
  color: #334155;
}

.status-dot {
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
}
.status-dot.online { background: #16a34a; }
.status-dot.offline { background: #94a3b8; }
.status-dot.warn { background: #d97706; }

.timestamp-jump {
  cursor: pointer;
  color: #0f766e;
  text-decoration: underline dotted;
}
.timestamp-jump:hover { color: #2563eb; }

.struct-bar {
  display: flex;
  height: 22px;
  border-radius: 8px;
  overflow: hidden;
  border: 1px solid var(--border);
  margin: 8px 0;
  font-size: 11px;
  color: #fff;
  font-weight: 600;
}
.struct-seg {
  display: flex;
  align-items: center;
  justify-content: center;
  white-space: nowrap;
  overflow: hidden;
  padding: 0 4px;
}

.word-cloud {
  display: flex;
  flex-wrap: wrap;
  gap: 6px;
  margin-top: 8px;
}
.word-chip {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  padding: 3px 10px;
  border-radius: 999px;
  background: #f0fdfa;
  border: 1px solid #99f6e4;
  color: #0f766e;
  font-size: 12px;
  font-weight: 600;
}

.cfs-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  margin-top: 8px;
}
@media (max-width: 760px) {
  .cfs-grid { grid-template-columns: 1fr; }
}
.cfs-card {
  padding: 8px 10px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: var(--surface-alt);
  font-size: 12px;
}

.compare-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 12.5px;
  margin-top: 8px;
}
.compare-table th, .compare-table td {
  border: 1px solid var(--border);
  padding: 7px 9px;
  text-align: left;
  vertical-align: top;
}
.compare-table th {
  background: #f8fafc;
  color: #0f172a;
  font-weight: 700;
}

.markdown-pre {
  white-space: pre-wrap;
  background: #f8fafc;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 12px;
  font-size: 12.5px;
  line-height: 1.55;
}