@media screen and (min-width: 360px){
    .a
    {
        margin-left:47.5%;
        margin-right:0px;
    }
    .col-md-6 hr
    {
        height:420px;
    }
}@media screen and (width: 320px){
    .a
    {
        margin-left:46.5%;
        margin-right:0px;
    }
    .col-md-6 hr
    {
        height:375px;
    }
}
@media screen and (min-width: 412px){
    .a
    {
        margin-left:48%;
        margin-right:0px;
    }
    .col-md-6 hr
    {
        height:480px;
    }
}
@media screen and (height: 667px){
   
    .col-md-6 hr
    {
        height:435px;
    }
}
@media screen and (height: 736px){
   
    .col-md-6 hr
    {
        height:482px;
    }
}
@media screen and (height: 1366px){
   
    .col-md-6 hr
    {
        height:600px;
    }
}