body {
  font-family: Arial, sans-serif;
  margin: 20px;
  background: #f4f4f9;
  color: #333;
}

header {
  margin-bottom: 20px;
}

h1 {
  text-align: center;
  color: #2c3e50;
}

h2 {
  margin-top: 20px;
  color: #34495e;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin: 10px 0 20px;
  background: white;
}

table, th, td {
  border: 1px solid #bbb;
}

th, td {
  padding: 8px 12px;
  text-align: center;
}

.unit-table {
  display: none;
  padding: 20px;
  border: 1px solid #ccc;
  background: #fff;
  margin-bottom: 20px;
  box-shadow: 0px 2px 5px rgba(0,0,0,0.1);
}

button {
  margin: 5px;
  padding: 8px 15px;
  background: #3498db;
  color: white;
  border: none;
  border-radius: 5px;
  cursor: pointer;
}

button:hover {
  background: #2980b9;
}

footer {
  text-align: center;
  margin-top: 30px;
  padding: 15px;
  background: #2c3e50;
  color: white;
}
footer a {
  color: #f1c40f;
  text-decoration: none;
}