body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: #eef5f9;
  color: #2c3e50;
}

header {
  background: #3498db;
  color: white;
  padding: 1.5rem;
  text-align: center;
}

main {
  max-width: 1000px;
  margin: 2rem auto;
  padding: 1rem;
}

.controls {
  display: flex;
  gap: 1rem;
  align-items: center;
  margin-bottom: 1.5rem;
}

select, button {
  padding: 0.6rem;
  font-size: 1rem;
}

button {
  border: none;
  background: #2980b9;
  color: white;
  border-radius: 4px;
  cursor: pointer;
}

button:hover {
  background: #2471a3;
}

.chart-container {
  background: white;
  padding: 1rem;
  border-radius: 6px;
  box-shadow: 0 2px 6px rgba(0,0,0,0.1);
}

.summary {
  margin-top: 1.5rem;
  background: #ecf0f1;
  padding: 1rem;
  border-radius: 6px;
}

footer {
  text-align: center;
  padding: 1rem;
  margin-top: 3rem;
  background: #dfe6e9;
}