.kl110 .a{background-image:url(a.jpg);}
.kl110 .f2:before{background-image:url(f2.jpg?1);}
@media (max-width:736px){
  .kl110 .a{background-image:url(m-a.jpg);}
  .kl110 .f2{background-image:url(m-f2.jpg?1);}
}