body {
  font-family: system-ui, sans-serif;
  margin: 0;
  background: #f7f9fb;
  color: #222;
}

header {
  background: #1f2937;
  color: white;
  padding: 24px;
  text-align: center;
}

main {
  max-width: 800px;
  margin: 30px auto;
  padding: 0 16px;
}

.calculator {
  background: white;
  padding: 24px;
  border-radius: 10px;
  box-shadow: 0 6px 18px rgba(0,0,0,0.08);
}

label {
  display: block;
  margin-top: 16px;
  font-weight: 600;
}

input, select, button {
  width: 100%;
  padding: 12px;
  margin-top: 6px;
  font-size: 16px;
}

button {
  margin-top: 20px;
  background: #2563eb;
  color: white;
  border: none;
  border-radius: 6px;
  cursor: pointer;
}

button:hover {
  background: #1e40af;
}

.results {
  margin-top: 20px;
  padding: 12px;
  background: #f1f5f9;
  border-radius: 6px;
}

.content {
  margin-top: 40px;
}

footer {
  margin-top: 60px;
  padding: 20px;
  background: #e5e7eb;
  text-align: center;
  font-size: 14px;
}

footer nav a {
  margin: 0 10px;
  color: #111;
  text-decoration: none;
}