#avatarUpload {display: inline-block; width: 50px; height: 50px; position: relative;}
#avatarUploadBtn {display: block; position: absolute; top: 0; left: 0; right: 0; bottom: 0;}
#avatarUploadBtn {opacity: 0; color: #fff; border-radius: 50%; line-height: 50px;}
#avatarUploadBtn:hover {opacity: 1; background-color: rgba(0,0,0,.5);}