Изменения

//background-image: url(//w.hil.su/images/8/8f/Scroll_top.png) no-repeat;

//-webkit-transition: opacity 0.4s easelinear; //transition: opacity 0.4s easelinear;

//background-color: rgba(255,255,255,1); //-webkit-transition: background-color 0.4s easelinear; //transition: background-color 0.4s ease; -webkit-transform:translateZ(0)linear;

//opacity: 1; //background-color: rgba(0,0,0,0.5);