#menu{
    background: url(https://image.flaticon.com/icons/svg/248/248921.svg)center  no-repeat;
    background-size: 50px 50px;
    background-color: aliceblue

}

#top{
    position: fixed;
    width: 60px;
    height: 60px;
    bottom: 10%;
    right: 5%;
    bottom: 0 ;
    z-index:1;
    background: url(https://image.flaticon.com/icons/svg/578/578922.svg)center  no-repeat;
    background-size: 35px 35px;
    background-color:lightsteelblue;
}
#top:hover{
    background-color:slategray;
}


input[type="checkbox"] {
    display:none;
}
input[type="checkbox"] + label span {
    display:inline-block;
    width:24px;
    height:24px;
    margin:-2px 10px 0 0;
    vertical-align:middle;
    background:url(https://image.flaticon.com/icons/svg/61/61218.svg) left top no-repeat;
    background-size: 24px 24px;
    cursor:pointer;
}
input[type="checkbox"]:checked + label span {
    background:url(https://image.flaticon.com/icons/svg/1828/1828644.svg) left top no-repeat;
    background-size: 24px 24px;

}