#rectangulo{
    position:absolute;
    background-color:blue;
    height:500px;
    border:7px dashed turquoise;
    top:75px;
    left:200px;
    width:300px;
}

#pantalla{
    position:absolute;
    background-color:turquoise;
    height:75px;  
    border:3px solid black;
    top:50px;
    left:25px;
    width:250px;
}               


#botones{
    position:absolute;
    background-color:lightgrey;
    border:3px solid black;
    left:25px;
    top:175px;  
    width:250px;
}

#numeros{
    background-color:turquoise;
    position:absolute;
    width:150px;
}

#operaciones{
    background-color:orange;
    position:absolute;
    left:150px;
}

button{
    border:none;
    color:black;
    padding:10px 15px;
    text-align: center;
    display: inline-block;
    font-size: 16px;
    margin: 4px 2px;
    cursor: pointer;
}


h3 {
    margin: 4px 4px;
    text-align: center;
}


h5 {
    text-align: center;
    background-color:turquoise;
}