#rectangulo {
    position:absolute;
    top:275px;
    left:500px;
    width:350px;
    height:500px;
    border:10px dashed black;
    background-color:orange
}


#pantalla {
    position:absolute;
    top:45px;
    left:10px;
    width:325px;
    height:150px;
    border:5px solid black;
    background-color:cyan
}

#marco {
    position:absolute; 
    top:215px;
    left:15px;
    width:300px;
    height:225px;
    border:5px solid black;
    background-color:grey
}

#botones {
    position:absolute;
    left:0px;
    top:0px;
    width:150px;
}

#operaciones {
    background-color:grey;
    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:right;
}

h5 {
    font-size:16px;
    text-align:center;
}