style.css

/* CSS comes here */
body {
    font-family: arial;
}

button {
    padding: 10px;
    background-color: #6a67ce;
    color: #FFFFFF;
    border: 0px;
    cursor: pointer;
    border-radius: 5px;
}

#output {
    background-color: #F9F9F9;
    padding: 10px;
    width: 100%;
    margin-top: 20px;
    line-height: 30px;
}

.hide {
    display: none;
}

.show {
    display: block;
}