* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

.container {
  margin: 10rem auto;
  width: 22rem;
  height: 28rem;
  background-color: rosybrown;
  box-shadow: 0 0 1rem 0 rgba(0, 0, 0, 0.2);
  border-radius: 1rem;
  display: flex;
  flex-direction: column;
  align-items: center;
}
.container .display-bar {
  margin: 2rem auto;
  width: 15rem;
  height: 2rem;
  border-radius: 1rem;
  box-shadow: 0 0 1rem 0 rgba(0, 0, 0, 0.2);
  border: none;
  background-color: #fafafa;
  font-family: sans-serif;
  font-size: large;
}
.container .buttons {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr 1fr;
  gap: 1rem;
}
.container .buttons .button {
  width: 3rem;
  height: 3rem;
  border-radius: 2rem;
  border: #4B4747;
  color: #fafafa;
  font-size: large;
  background-color: #4B4747;
}
.container .buttons .button--grey {
  background-color: #708090;
}
.container .buttons .button--color {
  background-color: #cd5c5c;
}
.container .buttons .button:hover {
  border: 2px solid #fafafa;
}