.clearfix:before, .clearfix:after, .grid-block:before, .grid-block:after {
    content: ".";
    display: block;
    height: 0;
    overflow: hidden;
}
.clearfix:after, .grid-block:after {
    clear: both;
}
.grid-box {
    float: left;
}
.width20 {
    width: 20%;
}
.width25 {
    width: 25%;
}
.width33 {
    width: 33.333%;
}
.width50 {
    width: 50%;
}