:root {
  --bg: #0f172a;
  --bg2: #1e293b;
  --card: rgba(30, 41, 59, 0.85);
  --border: rgba(148, 163, 184, 0.15);
  --text: #f8fafc;
  --dim: #94a3b8;
  --dimmer: #64748b;
  --primary: #3b82f6;
  --secondary: #8b5cf6;
  --accent: #f59e0b;
  --success: #10b981;
  --warn: #eab308;
  --danger: #ef4444;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Inter', 'PingFang SC', sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.7;
  min-height: 100vh;
}

.top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 24px;
  background: var(--bg2);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.top-bar h1 {
  font-size: 18px;
  font-weight: 700;
  background: linear-gradient(135deg, var(--accent), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

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

.nav-links a {
  color: var(--dim);
  text-decoration: none;
  padding: 6px 12px;
  border-radius: 6px;
  font-size: 13px;
  transition: all 0.2s;
}

.nav-links a:hover, .nav-links a.active {
  color: var(--text);
  background: rgba(59, 130, 246, 0.15);
}

.container { max-width: 1280px; margin: 0 auto; padding: 32px 24px 64px; }

.hero {
  text-align: center;
  padding: 48px 24px 32px;
  background: linear-gradient(135deg, rgba(245, 158, 11, 0.08), rgba(139, 92, 246, 0.06));
}

.hero h2 {
  font-size: 36px;
  font-weight: 800;
  margin-bottom: 12px;
  background: linear-gradient(135deg, var(--accent), var(--secondary));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero p { color: var(--dim); max-width: 720px; margin: 0 auto; font-size: 15px; }

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 20px;
  margin-top: 32px;
}

.mode-card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px;
  transition: transform 0.2s, border-color 0.2s;
  cursor: pointer;
  text-decoration: none;
  color: inherit;
  display: block;
}

.mode-card:hover {
  transform: translateY(-2px);
  border-color: rgba(245, 158, 11, 0.35);
}

.mode-card .icon { font-size: 32px; margin-bottom: 12px; }
.mode-card h3 { font-size: 18px; margin-bottom: 8px; }
.mode-card p { font-size: 13px; color: var(--dim); }

.panel {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 24px;
  margin-bottom: 24px;
}

.panel-title {
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.form-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
}

.form-grid .full { grid-column: 1 / -1; }

label {
  display: block;
  font-size: 13px;
  color: var(--dim);
  margin-bottom: 6px;
}

input, select, textarea {
  width: 100%;
  padding: 10px 12px;
  border-radius: 8px;
  border: 1px solid var(--border);
  background: rgba(15, 23, 42, 0.6);
  color: var(--text);
  font-size: 14px;
  font-family: inherit;
}

textarea { min-height: 88px; resize: vertical; }

.field-hint { font-size: 12px; color: var(--dimmer); margin-top: 6px; }

.shell-badge {
  display: inline-block;
  padding: 4px 10px;
  border-radius: 999px;
  font-size: 12px;
  background: rgba(59, 130, 246, 0.15);
  color: var(--primary);
  margin-bottom: 8px;
}

.btn {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 10px 20px;
  border-radius: 8px;
  border: none;
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  transition: opacity 0.2s;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent), #d97706);
  color: #0f172a;
}

.btn-secondary {
  background: rgba(59, 130, 246, 0.2);
  color: var(--text);
  border: 1px solid rgba(59, 130, 246, 0.3);
}

.btn:hover { opacity: 0.9; }

.stat-row {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 20px;
}

.stat-box {
  flex: 1;
  min-width: 120px;
  padding: 16px;
  border-radius: 10px;
  background: rgba(15, 23, 42, 0.5);
  border: 1px solid var(--border);
}

.stat-box .num { font-size: 28px; font-weight: 800; }
.stat-box .lbl { font-size: 12px; color: var(--dim); }

.cov-green { color: var(--success); }
.cov-yellow { color: var(--warn); }
.cov-red { color: var(--danger); }

.matrix-wrap { overflow: auto; max-height: 520px; border-radius: 10px; border: 1px solid var(--border); }

.coverage-matrix {
  border-collapse: collapse;
  font-size: 11px;
  min-width: 100%;
}

.coverage-matrix th, .coverage-matrix td {
  padding: 6px 8px;
  border: 1px solid var(--border);
  white-space: nowrap;
}

.coverage-matrix th {
  background: var(--bg2);
  position: sticky;
  top: 0;
  z-index: 2;
}

.coverage-matrix .node-col {
  position: sticky;
  left: 0;
  background: var(--bg2);
  z-index: 1;
  max-width: 200px;
  overflow: hidden;
  text-overflow: ellipsis;
}

.cell-core { background: rgba(16, 185, 129, 0.25); text-align: center; }
.cell-mention { background: rgba(234, 179, 8, 0.2); text-align: center; }
.cell-gap { background: rgba(239, 68, 68, 0.08); text-align: center; color: var(--dimmer); }

.legend { display: flex; gap: 16px; font-size: 12px; color: var(--dim); margin-bottom: 12px; }
.legend span { display: flex; align-items: center; gap: 6px; }
.legend i { width: 12px; height: 12px; border-radius: 2px; display: inline-block; }

.dual-form-divider {
  border-left: 3px solid var(--accent);
  padding-left: 16px;
  margin: 8px 0;
}

.inspiration-chip {
  display: inline-block;
  padding: 4px 10px;
  margin: 4px 4px 0 0;
  border-radius: 999px;
  font-size: 12px;
  background: rgba(148, 163, 184, 0.1);
  color: var(--dim);
  cursor: pointer;
  border: 1px dashed var(--border);
}

.inspiration-chip:hover { border-color: var(--accent); color: var(--text); }

.diversity-bar {
  height: 8px;
  border-radius: 4px;
  background: var(--bg2);
  overflow: hidden;
  margin-top: 8px;
}

.diversity-bar-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--success), var(--accent));
  transition: width 0.4s;
}

.student-row {
  display: grid;
  grid-template-columns: 1fr auto auto;
  gap: 12px;
  align-items: center;
  padding: 12px;
  border-bottom: 1px solid var(--border);
}

@media (max-width: 768px) {
  .form-grid { grid-template-columns: 1fr; }
  .student-row { grid-template-columns: 1fr; }
}