#button {
    display: inline-block;
    background-color: #4D504D;
    width: 50px;
    height: 50px;
    text-align: center;
    border-radius: 30px;
    position: fixed;
    bottom: 30px;
    right: 30px;
    transition: background-color .3s, opacity .5s, visibility .5s;
    opacity: 0;
    visibility: hidden;
    z-index: 1000;
    
    box-shadow: -1px 1px 35px -4px rgba(0,0,0,0.75);
    -webkit-box-shadow: -1px 1px 35px -4px rgba(0,0,0,0.75);
    -moz-box-shadow: -1px 1px 35px -4px rgba(0,0,0,0.75);
}
#button::after {
    content: "🡡";
    font-family: FontAwesome;
    font-weight: normal;
    font-style: normal;
    font-size: 2em;
    line-height: 50px;
    color: #fff;
}
#button:hover {
    cursor: pointer;
    background-color: #333;
}
#button:active {
    background-color: #555;
}