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

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  background: #f5f5f5;
  color: #333;
  padding: 1.5rem;
  max-width: 1200px;
  margin: 0 auto;
}

h1 {
  font-size: 1.5rem;
  margin-bottom: 1rem;
}

nav#tabs {
  display: flex;
  gap: 0.25rem;
  margin-bottom: 1.5rem;
  border-bottom: 2px solid #ddd;
}

nav#tabs button {
  padding: 0.5rem 1.25rem;
  border: none;
  background: transparent;
  font-size: 0.95rem;
  cursor: pointer;
  border-bottom: 2px solid transparent;
  margin-bottom: -2px;
  color: #666;
  transition: color 0.15s, border-color 0.15s;
}

nav#tabs button:hover {
  color: #111;
}

nav#tabs button.active {
  color: #111;
  border-bottom-color: #2563eb;
  font-weight: 600;
}

.device-panel {
  display: none;
}

.device-panel.active {
  display: block;
}

.chart-card {
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.08);
  padding: 1rem 1.25rem;
  margin-bottom: 1.25rem;
}

.chart-card h2 {
  font-size: 1rem;
  font-weight: 600;
  margin-bottom: 0.75rem;
  color: #444;
}

.chart-card canvas {
  width: 100% !important;
  height: 280px !important;
}