.main {
    background-image: url(../images/bg.jpg);
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    z-index: -200;
    background-repeat: no-repeat;
    background-size: cover;
}
a{
    text-decoration:none;
}
    a:hover {
        box-shadow: 1px 3px 3px 0 rgba(0, 0, 0, 0.2), 1px 3px 15px 2px rgba(0, 0, 0, 0.2);
    }
#chrome {
    background-image: url("../images/chrome.png");
    background-repeat: no-repeat;
    background-position: center 20px;
    background-size: 92px;
}

    #chrome:hover {

    }
#jisu360 {
    background-image: url("../images/jisu360.png");
    background-repeat: no-repeat;
    background-position: center 20px;
    background-size: 92px;
}

    #jisu360:hover {
    }
#b360 {
    background-image: url("../images/360.jpg");
    background-repeat: no-repeat;
    background-position: center 20px;
    background-size: 92px;
}

    #b360:hover {
    }

#qq {
    background-image: url("../images/qq.png");
    background-repeat: no-repeat;
    background-position: center 20px;
    background-size: 92px;
}

    #qq:hover {

    }
#maxthon {
    background-image: url("../images/maxthon.png");
    background-repeat: no-repeat;
    background-position: center 20px;
    background-size: 92px;
}

    #maxthon:hover {
    }