:root {
  --primary: #6366f1;
  --primary-dark: #4f46e5;
  --bg: #f8fafc;
  --card-bg: #ffffff;
  --text: #1e293b;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --success: #22c55e;
  --warning: #f59e0b;
  --danger: #ef4444;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  background: var(--bg);
  color: var(--text);
  line-height: 1.6;
}

/* Layout */
.app { display: flex; min-height: 100vh; }

.sidebar {
  width: 220px;
  background: #1e293b;
  color: #e2e8f0;
  padding: 20px 0;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  overflow-y: auto;
}

.sidebar .logo {
  font-size: 18px;
  font-weight: 700;
  padding: 0 20px 20px;
  border-bottom: 1px solid #334155;
  color: #fff;
}

.sidebar nav { padding: 16px 0; }

.sidebar a {
  display: block;
  padding: 10px 20px;
  color: #94a3b8;
  text-decoration: none;
  font-size: 14px;
  transition: all 0.2s;
}

.sidebar a:hover, .sidebar a.active {
  color: #fff;
  background: #334155;
}

.sidebar a.active { border-left: 3px solid var(--primary); }

.main {
  margin-left: 220px;
  flex: 1;
  padding: 24px;
  max-width: 1400px;
}

/* Header */
.header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 24px;
  flex-wrap: wrap;
  gap: 12px;
}

.header h1 { font-size: 24px; font-weight: 600; }

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

/* Cards */
.kpi-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}

.kpi-card {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 20px;
  border: 1px solid var(--border);
}

.kpi-card .label {
  font-size: 12px;
  text-transform: uppercase;
  color: var(--text-muted);
  font-weight: 600;
  letter-spacing: 0.5px;
}

.kpi-card .value {
  font-size: 28px;
  font-weight: 700;
  margin-top: 4px;
}

.kpi-card .change {
  font-size: 13px;
  margin-top: 4px;
}

.kpi-card .change.up { color: var(--success); }
.kpi-card .change.down { color: var(--danger); }

/* Metric cards (headline number + sparkline) */
.metric-grid {
  display: grid;
  /* minmax(0,1fr) stops the sparkline <canvas> (intrinsic 300px) from forcing track width */
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}

.metric-card {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 20px;
  border: 1px solid var(--border);
}

.metric-card .label {
  font-size: 12px;
  text-transform: uppercase;
  color: var(--text-muted);
  font-weight: 600;
  letter-spacing: 0.5px;
}

.metric-card .value {
  font-size: 28px;
  font-weight: 700;
  margin-top: 4px;
}

.metric-card .sub {
  font-size: 12px;
  color: var(--text-muted);
  margin-top: 2px;
}

.metric-card .spark {
  position: relative;
  height: 48px;
  margin-top: 8px;
}

/* Charts */
.chart-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(500px, 1fr));
  gap: 16px;
  margin-bottom: 24px;
}

.chart-card {
  background: var(--card-bg);
  border-radius: 12px;
  padding: 20px;
  border: 1px solid var(--border);
}

.chart-card h3 {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 16px;
}

.chart-container {
  position: relative;
  height: 300px;
}

/* Full-width featured card + header actions */
.chart-card.wide { grid-column: 1 / -1; }

.card-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 16px;
}

.card-head h3 { margin-bottom: 0; }
.card-note { font-size: 12px; color: var(--text-muted); margin-top: 4px; }

.card-actions { display: flex; gap: 6px; }

.btn-sm {
  padding: 4px 12px;
  font-size: 13px;
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-sm.active {
  background: var(--primary);
  color: #fff;
  border-color: var(--primary);
}

/* Table */
table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

th, td {
  padding: 10px 12px;
  text-align: left;
  border-bottom: 1px solid var(--border);
}

th {
  background: var(--bg);
  font-weight: 600;
  font-size: 12px;
  text-transform: uppercase;
  color: var(--text-muted);
}

/* Retention grid */
.retention-grid td {
  text-align: center;
  font-size: 13px;
  min-width: 60px;
}

.retention-grid .cell-high { background: #dcfce7; }
.retention-grid .cell-med { background: #fef9c3; }
.retention-grid .cell-low { background: #fee2e2; }
/* Not-yet-measurable cell (cohort too young for this bucket) — neutral, not a red 0% */
.retention-grid .cell-na { color: var(--text-muted); text-align: center; }

/* Forms */
select, input[type="text"], input[type="date"], input[type="email"], input[type="password"] {
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: 8px;
  font-size: 14px;
  background: var(--card-bg);
  color: var(--text);
}

select:focus, input:focus { outline: none; border-color: var(--primary); }

button, .btn {
  padding: 8px 16px;
  border: none;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.2s;
}

.btn-primary {
  background: var(--primary);
  color: #fff;
}

.btn-primary:hover { background: var(--primary-dark); }

.btn-secondary {
  background: var(--bg);
  color: var(--text);
  border: 1px solid var(--border);
}

.btn-danger { background: var(--danger); color: #fff; }

/* Inline notice / error banner */
.notice {
  background: #fef3c7;
  border: 1px solid #fde68a;
  color: #92400e;
  padding: 12px 16px;
  border-radius: 8px;
  margin-bottom: 16px;
  font-size: 14px;
}
.notice.error { background: #fee2e2; border-color: #fecaca; color: #991b1b; }

/* Login */
.login-container {
  max-width: 400px;
  margin: 100px auto;
  padding: 40px;
  background: var(--card-bg);
  border-radius: 16px;
  border: 1px solid var(--border);
  box-shadow: 0 4px 20px rgba(0,0,0,0.08);
}

.login-container h1 {
  text-align: center;
  margin-bottom: 24px;
}

.form-group {
  margin-bottom: 16px;
}

.form-group label {
  display: block;
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 4px;
  color: var(--text-muted);
}

.form-group input {
  width: 100%;
}

.error-msg {
  color: var(--danger);
  font-size: 13px;
  margin-top: 8px;
  display: none;
}

/* Realtime feed */
.event-feed {
  max-height: 600px;
  overflow-y: auto;
}

.event-row {
  padding: 8px 12px;
  border-bottom: 1px solid var(--border);
  font-family: monospace;
  font-size: 13px;
  display: flex;
  gap: 16px;
}

.event-row .time { color: var(--text-muted); min-width: 80px; }
.event-row .name { color: var(--primary); font-weight: 600; min-width: 150px; }
.event-row .user { color: var(--text-muted); min-width: 100px; }

/* Funnel */
.funnel-step {
  display: flex;
  align-items: center;
  gap: 12px;
  margin-bottom: 8px;
}

.funnel-step input {
  flex: 1;
}

/* Loading */
.loading {
  text-align: center;
  padding: 40px;
  color: var(--text-muted);
}

/* Explore — event hierarchy tree */
.event-tree {
  max-height: 380px;
  overflow-y: auto;
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 4px 0;
  font-size: 14px;
}

.tree-node {
  display: flex;
  align-items: center;
  padding: 6px 12px;
  cursor: pointer;
  user-select: none;
  border-left: 3px solid transparent;
  gap: 8px;
}

.tree-node:hover { background: var(--bg); }

.tree-node.active {
  background: rgba(99, 102, 241, 0.10);
  border-left-color: var(--primary);
  color: var(--primary-dark);
  font-weight: 600;
}

.tree-node.tree-root {
  padding-left: 12px;
  font-weight: 600;
  border-bottom: 1px solid var(--border);
  margin-bottom: 4px;
}

.tree-toggle {
  width: 14px;
  display: inline-block;
  text-align: center;
  color: var(--text-muted);
  font-size: 11px;
}

.tree-label {
  flex: 1;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.tree-count {
  font-size: 12px;
  color: var(--text-muted);
  background: var(--bg);
  padding: 2px 8px;
  border-radius: 10px;
  font-variant-numeric: tabular-nums;
}

.tree-node.active .tree-count {
  background: rgba(99, 102, 241, 0.18);
  color: var(--primary-dark);
}

/* Explore — metric / dimension control row */
.explore-controls {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 12px;
}

.explore-controls label {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-muted);
  display: block;
  margin-bottom: 4px;
}

.explore-controls select,
.explore-controls input {
  width: 100%;
}

/* Responsive */
@media (max-width: 1100px) {
  .metric-grid { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (max-width: 768px) {
  .sidebar { display: none; }
  .main { margin-left: 0; padding: 16px; }
  .chart-grid { grid-template-columns: 1fr; }
  .metric-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
}