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

html {
  font-size: 16px;
}

body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  font-family: "Roboto", serif;
  font-weight: 400;
  font-style: normal;
  background-color: #1c1c1c;
}

.calculator {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: auto repeat(5, 1fr);
  gap: 10px;
  width: 320px;
}

#display {
  display: flex;
  justify-content: flex-end;
  align-items: center;
  grid-column: span 4;
  background-color: #505050;
  color: #fff;
  padding: 20px;
  font-size: 2rem;
  overflow: hidden;
}

.calculator button {
  cursor: pointer;
  border: none;
  font-size: 1.5rem;
  padding: 20px;
  font-family: "Roboto", serif;
  font-weight: 400;
  font-style: normal;
  background-color: #505050;
  color: #fff;
}

.calculator button:active {
  background-color: #3b3b3b;
}

.calculator button.selected {
  background-color: #fff;
  color: #ff9500;
}

.calculator button:disabled,
.calculator button:disabled:active {
  background-color: #3b3b3b;
  opacity: 0.5;
}

.calculator button[value="0"] {
  grid-column: span 2;
}

button.light-gray-button {
  background-color: #d4d4d2;
  color: #1c1c1c;
}

button.light-gray-button:active {
  background-color: #bfbfbf;
}

button.orange-button {
  background-color: #ff9500;
  color: #fff;
}

button.orange-button:active {
  background-color: #cc7a00;
}