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

.calculator {
  border: 2px solid black;
  padding: 10px;
  border-radius: 5px;
}

table {
  margin-top: 10px;
}

button {
  font-size: 1.2rem;
  width: 50px;
  height: 50px;
  border-radius: 50%;
  border: 2px solid black;
  margin: 5px;
  background-color: lightpink;
}

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

button:active {
  background-color: #bbb;
}