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

body {
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  background-color: #c4c4c4;
}

.calculator {
  background-color: #f2f2f2;
  width: 25rem;
  padding: 1.5rem;
  border: solid 1px #ccc;
  border-radius: 5px;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.3);
}

.result {
  width: 100%;
  padding: 0.5rem;
  font-size: 1.5rem;
  border: none;
  outline: none;
  box-shadow: 0 2px 5px rgba(0, 0, 0, 0.3) inset;
  border-radius: 5px;
}

.buttons {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 0.5rem;
  margin-top: 1.25rem;
}

button {
  padding: 0.5rem;
  font-size: 1.5rem;
  border: none;
  border-radius: 5px;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.3);
  cursor: pointer;
  transition: background-color 0.3s;
}

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

.clear {
  background-color: #ff4136;
  color: #fff;
}

.number,
.decimal {
  background-color: #fff;
  color: #333;
}

.operator {
  background-color: #0074d9;
  color: #fff;
}

.equals {
  background-color: #01ff70;
  grid-row: span 3;
  color: #fff;
}