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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  background: #f5f6fa;
  color: #2c3e50;
  line-height: 1.6;
}

header {
  background: #2c3e50;
  color: #fff;
  padding: 1rem 2rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 1rem;
}

header h1 {
  font-size: 1.4rem;
  font-weight: 600;
}

.controls {
  display: flex;
  gap: 0.5rem;
  align-items: center;
  flex-wrap: wrap;
}

.controls select, .controls button {
  padding: 0.4rem 0.8rem;
  border: 1px solid #4a6fa5;
  border-radius: 4px;
  background: #34495e;
  color: #fff;
  font-size: 0.9rem;
  cursor: pointer;
}

.controls select:hover, .controls button:hover {
  background: #4a6fa5;
}

main {
  max-width: 1200px;
  margin: 0 auto;
  padding: 1.5rem;
}

/* Latest readings cards */
.latest-cards {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 1rem;
  margin-bottom: 1.5rem;
}

.latest-cards .placeholder {
  grid-column: 1 / -1;
  text-align: center;
  color: #95a5a6;
  padding: 2rem;
}

.card {
  background: #fff;
  border-radius: 8px;
  padding: 1rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
  text-align: center;
}

.card .label {
  font-size: 0.75rem;
  color: #7f8c8d;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 0.3rem;
}

.card .value {
  font-size: 1.8rem;
  font-weight: 700;
  color: #2c3e50;
}

.card .unit {
  font-size: 0.85rem;
  color: #95a5a6;
  margin-left: 2px;
}

.card .time {
  font-size: 0.7rem;
  color: #bdc3c7;
  margin-top: 0.3rem;
}

/* Chart */
.chart-section {
  background: #fff;
  border-radius: 8px;
  padding: 1rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
  margin-bottom: 1.5rem;
}

.chart-controls {
  margin-bottom: 0.5rem;
}

.metric-checkboxes {
  display: flex;
  flex-wrap: wrap;
  gap: 0.8rem;
  font-size: 0.85rem;
}

.metric-checkboxes label {
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: 0.3rem;
}

.chart-container {
  position: relative;
  height: 400px;
}

/* Table */
.table-section {
  background: #fff;
  border-radius: 8px;
  padding: 1rem;
  box-shadow: 0 1px 3px rgba(0,0,0,0.1);
}

.table-section summary {
  cursor: pointer;
  font-weight: 600;
  color: #2c3e50;
}

.table-wrapper {
  overflow-x: auto;
  margin-top: 1rem;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 0.85rem;
}

th, td {
  padding: 0.5rem 0.8rem;
  text-align: left;
  border-bottom: 1px solid #ecf0f1;
}

th {
  background: #f8f9fa;
  font-weight: 600;
  color: #2c3e50;
  position: sticky;
  top: 0;
}

tr:hover {
  background: #f8f9fa;
}

/* Footer */
footer {
  text-align: center;
  padding: 1rem;
  color: #95a5a6;
  font-size: 0.8rem;
}

/* Responsive */
@media (max-width: 768px) {
  header {
    padding: 0.8rem 1rem;
  }
  header h1 {
    font-size: 1.1rem;
  }
  main {
    padding: 1rem;
  }
  .chart-container {
    height: 300px;
  }
  .latest-cards {
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
  }
}