estilo.css

h2 {
    font-family: Arial, Helvetica, sans-serif;
    margin-left: 55px;
    color: rgb(78, 78, 78);
}

#visor,
#visor2 {
    width: 250px;
    height: 50px;
    text-align: right;
    font-size: 20px;
    background-color: rgb(212, 237, 245);
    box-shadow: inset -2px -2px 5px 1px rgba(0, 0, 0, 0.3);
    color: rgb(59, 157, 223);
    font-size: 36px;
}

button {
    width: 60px;
    height: 60px;
    padding: 10px;
    font-size: 20px;
    background-color: lightgray;
}

button:hover {

    background-color: rgb(250, 215, 176);
}

div {
    width: 400px;
    padding: 50px;
}

.calc {
    width: 250px;
}