index.css

html, body {
    margin: 0px;
    padding: 0px;
}

textarea {
    resize: none;
}

.doc {
    height: 100%;
    width: 50%;
    padding: 10px;
    z-index: 0;
    outline: none;
    border: 0px;
    color: white;
    font-family: Helvetica;
    font-size: 20px;
}

#doc1{
    float: left;
    background-color: #34495e;
}

#doc2{
    float: right;
    background-color: #2c3e50;
}

#compare-btn{
    position: absolute;
    z-index: 1;
    height: 70px;
    width: 150px;
    bottom: 10px;
    right: calc(50% - 75px);
    background-color: #2ecc71;
    border: 0px;
    border-radius: 3px;
    cursor: pointer;
    -webkit-box-shadow: 0px 0px 19px 0px rgba(0,0,0,0.75);
    -moz-box-shadow: 0px 0px 19px 0px rgba(0,0,0,0.75);
    box-shadow: 0px 0px 19px 0px rgba(0,0,0,0.75);
    color: white;
    font-size: 24px;
}

#compare-btn:not([disabled]):hover {
    background-color: #27ae60; 
}

::-webkit-scrollbar {
    display: none;
}