body, html{
    background-color: lightgray;
}
div#calculadora{
    margin: auto;
    width: 550px;
    height: 700px;
    border: none;
    background-color: #363636;
    border-radius: 32px;
    font-family: 'Orbitron', 'sans-serif';
    box-shadow: inset;
    box-shadow: 10px 10px 15px 3px;
}

#screen{
    font-family: inherit;
    font-size: 60px;
    width: 510px;
    height: 130px;
    margin: 40px 20px;
    border: none;
    border-radius: 24px;
    box-shadow: inset 5px 5px 30px;
    background-color: white;
}

#botoesCalculadora{
    margin-left: 20px;
    display: grid;
    grid-template-columns: 95px 95px 95px 95px 95px;
    grid-gap: 8px;
    grid-template-rows: 100px 100px 100px 100px 100px;
}

button{
    outline: none;
    border-radius: 12px;
    cursor: pointer;
    border: none;
    background-color: dimgray;
    color: whitesmoke;
    font: inherit;
    font-size: 25px;
    box-shadow: 5px 3px 5px black;
}

button:hover{
    box-shadow: inset 5px 3px 15px black;
    background-color: #363636;
}

#resultado{
    height: 206px;
    font-size: 60px;
    background-color: #2ECC71;
}

#limpar{
    font-size: 30px;
}

#github {
    position: absolute;
    bottom: 8px;
    right: 21px;
}

div#calculadora{
    position: relative;
    /* restante do código */
}

#github img {
    border-radius: 15px;
    width: 140px;
    height: auto;
}

#github:hover {
    animation: pulse 1s infinite;
}
@keyframes pulse {
    0% {
        transform: scale(1);
    }
    50% {
        transform: scale(1.1);
    }
    100% {
        transform: scale(1);
    }
}