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;
}

.display {
    grid-column: 1 / 5;
    height: 50px;
    width: 200px;
}

button {
    height: 50px;
}

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

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