.one-half, .one-third, .two-third, .one-fourth {
    float: left;
    min-height: 1px;
    padding: 0 20px;
}

.one-half {
    width: 50%;
}

.one-third {
    width: 33.33%;
}

.two-third {
    width: 66.66%;
}

.one-fourth {
    width: 25%;
}