* {
 box-sizing: border-box;
}
header {
    border: 2px solid red;
    padding: 15px;
	font-family: Verdana, Geneva, sans-serif;
	font-size:2.0em;
	background-color: lightgreen;
}
body{
	font-family:Verdana, Geneva, sans-serif;
	font-size: 0.6em;
}
.row::after {
    content: "";
    clear: both;
    display: table;
}
[class*="col-"] {
    float: left;
    padding: 15px;
    /*border: 1px solid red;*/
}
/* 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%;}

img{
	width: 100%;
    height: auto;
    }
@media only screen and (max-width: 768px) {
    /* For mobile phones: */
    [class*="col-"] {
        width: 100%;
    }
     body {
        background-color: lightblue;
        font-family:Verdana, Geneva, sans-serif;
        font-size: 0.6em;
    }
    img{
	width: 90%;
    height: auto;
    }
header {
    border: 2px solid blue;
    padding: 15px;
	font-family: Verdana, Geneva, sans-serif;
	font-size:1.9em;
	background-color: #FFBBBB;

}
}