* {
  box-sizing: border-box;
  font-family: Arial;
}

h1 {
  text-align: center;
  color: navy;
}

.calculator {
  margin: 0 auto;
  width: 250px;
  border: 1px solid black;
  border-radius: 5px;
  padding: 10px;
}

table {
  border-collapse: collapse;
  margin: 0 auto;
}

input[type=text] {
  width: 100%;
  height: 40px;
  font-size: 20px;
  margin-bottom: 10px;
  text-align: right;
  border: none;
  background: none;
  outline: none;
}

button {
  width: 100%;
  height: 40px;
  font-size: 20px;
  border: 1px solid black;
  border-radius: 5px;
  background-color: #eee;
  cursor: pointer;
  outline: none;
}

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

.clear {
  background-color: orangered;
  color: white;
}

.backspace {
  font-size: 25px;
}

.number {
  background-color: white;
}

.operation {
  background-color: #f5f5f5;
}

.equals {
  background-color: #007bff;
  color: white;
}