/*样式*/
.pic {
    /*padding-top: 75%;*/
    position: relative;
    overflow: hidden;}

.pic .a{
    position: absolute;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    background-position: 50%;
    background-repeat: no-repeat;
    background-size: cover;
    transition: all 0.3s ease-in;}
.bg-mask:hover .pic .a {
    transform: scale(1.1);}
.pic img:hover,
.bg-mask:hover .cover_img .a{
    transform: scale(1.05);}