.about_choose .bg:before{content:"";width:100%;height:63%;position:absolute;left:0;top:0;background:linear-gradient(#012f6a,#021c3200)}.about_choose .bg:after{content:"";width:100%;height:100%;background:linear-gradient(#021c3200,#012f6a);position:absolute;left:0;top:0}