* {
    box-sizing: border-box;
  }  

@media screen and (orientation: landscape){
/* For desktop: */
.col-1 {width: 8.33%;}
.col-2 {width: 16.66%;}
.col-3 {width: 25%;}
.col-4 {width: 33.33%;}
.col-5 {width: 41.66%;}
.col-6 {width: 50%;}
.col-7 {width: 58.33%;}
.col-8 {width: 66.66%;}
.col-9 {width: 75%;}
.col-10 {width: 83.33%;}
.col-11 {width: 91.66%;}
.col-12 {width: 100%;}

@media only screen and (orientation: portrait) {
    /* For mobile phones: */
    [class*="col-"] {
        width: 100%;
    }
}


[class*="col-"]
{
 float: left;
 padding: 15px;
 border: 1px solid red;
}