body {
  font-family: Arial, sans-serif;
  background-color: #f3f4f6;
  color: #333;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  margin: 0;
  flex-direction: column;
}

.calculator {
  background: #ffffff;
  border-radius: 10px;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
  padding: 20px;
}

h1 {
  text-align: center;
  font-size: 24px;
  color: #4a5568;
}

output {
  display: block;
  background: #f7fafc;
  border: 1px solid #e2e8f0;
  border-radius: 5px;
  padding: 15px;
  font-size: 24px;
  text-align: right;
  margin-bottom: 20px;
}

div > div {
  display: flex;
  gap: 10px;
  margin-bottom: 10px;
}

button {
  flex: 1;
  padding: 15px;
  font-size: 18px;
  font-weight: bold;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  background-color: #e2e8f0;
  color: #333;
  transition: all 0.2s;
  min-width: 60px;
}

button:hover {
  background-color: #cbd5e0;
}

button:active {
  background-color: #a0aec0;
}

button[aria-label="Delete"],
button[aria-label="All Clear"] {
  background-color: #f56565;
  color: #fff;
  flex: 1;
  text-align: center;
  flex-shrink: 0;
}

button[aria-label="Delete"]:hover,
button[aria-label="All Clear"]:hover {
  background-color: #e53e3e;
}

button[aria-label="Multiply"],
button[aria-label="Divide"],
button[aria-label="Add"],
button[aria-label="Subtract"] {
  background-color: #63b3ed;
  color: #fff;
}

button[aria-label="Multiply"]:hover,
button[aria-label="Divide"]:hover,
button[aria-label="Add"]:hover,
button[aria-label="Subtract"]:hover {
  background-color: #4299e1;
}