.case_fixed_img{
    padding-top: 52%;
    background-attachment:fixed;
    background-position: center;
    background-repeat: no-repeat; 
    background-size:cover;
    position: relative;
    z-index: 10;
    image-rendering: auto;
    image-rendering: crisp-edges
}
.case_fixed_img .before{position: absolute;left: 0;top: 0px;height: 100%;width: 14%;background: #fff;-webkit-transform: translateX(0);transform: translateX(0);}
.case_fixed_img .after{position: absolute;right: 0;top: 0px;height: 100%;width: 14%;background: #fff;-webkit-transform: translateX(0);transform: translateX(0);}

.case_fixed_img .case_tit{position: absolute;
  left:13%;
  width:74%;
  top: 50%;
  -webkit-transform: translateY(-50%);
  -ms-transform: translateY(-50%);
  -o-transform: translateY(-50%);
  transform: translateY(-50%);
}

.case_fixed_img .case_tit h3{color: #fff; font-size:calc(1.8rem + 1vw);}
.case_fixed_img .case_tit h4{color: #fff;line-height: 1.7;margin-top:1px;}
.pageWrapper {
    position: absolute;
    top: 0px;
    left: 0px;
    bottom: 0px;
    right: 0;
    height: 100%;
    width: 100%;
    overflow: hidden;
}

 @media screen and (max-width: 640px){
	.case_fixed_img{padding-top:105%!important;}
	.case_fixed_img .case_tit{left: 6.5%;width:87%;}
}