.calculadora {
    display: flex;
	justify-content: center;
	margin-top: 35px
}

button {
	margin: 2px 0px;
	padding: 15px 24px;
    font-size: 15px;
}


.teclas {
    display: grid;
    justify-content: center;
    width: 250px;
    background-color: black;
}


.pantalla {
    width: 220px;
    height: 100px;
    background-color: gray;
    border: 1px solid black;
}