背景层样式：

.index-adv{ 
    width:100%; 
    height:600px; 
    background:url(../images/brand1.jpg) no-repeat 50% 50%; 
    background-size:1920px; 
    transition:all ease-out 5s;
    -moz-transition:all ease-out 5s;
    -webkit-transition:all ease-out 5s;
    -o-transition:all ease-out 5s;
    -ms-transition:all ease-out 5s;
}

背景层鼠标悬浮样式：

.index-adv:hover{
    background-size:2200px;
}