/* Optional, aber für Bootstrap-Grid sinnvoll */
.row:before,
.row:after {
    display: table;
    content: " ";
}

.row:after {
    clear: both;
}

/* Grundregel für die verwendeten Spalten */
.col-xs-12,
.col-sm-3,
.col-lg-3 {
    position: relative;
    min-height: 1px;
    padding-right: 0;
    padding-left: 0;
}

/* XS: volle Breite */
.col-xs-12 {
    float: left;
    width: 100%;
}

/* SM: ab 768px = 3/12 = 25% */
@media (min-width: 768px) {
    .col-sm-3 {
        float: left;
        width: 25%;
    }
}

/* LG: ab 1200px = 3/12 = 25% */
@media (min-width: 1200px) {
    .col-lg-3 {
        float: left;
        width: 25%;
    }
}