body {
  font-family: "Roboto Mono", monospace;
  font-optical-sizing: auto;
  font-weight: 400;
  font-style: normal;
  display: flex;
  align-items: center;
  justify-content: center;
  height: 100vh;
}

.calculator {
    display: grid;
    grid-template-columns: 1fr 1fr 1fr 1fr;
    border-collapse: collapse;
    border-radius: 0;
}

#display {
    grid-column: 1 / 5;
    height: 100px;
    width: 400px;
    background-color: black;
    color: white;
    text-align: right;
    font-size: 75px;
}

button {
    height: 100px;
    font-size: 50px;
    background-color: #d8d9db;
    border: 1px solid black;
    padding: 0;

}

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

.operator {
    background-color: #df974c;
    color: white;
}

.operator:hover {
    background-color: #dfb07e;
}

.clear {
    grid-column: 1 / 3;
}

.zero {
    grid-column: 1 / 4;
}