.grid {
    width: 90%;
    margin: 5%;
    text-align:center;
}

.gridelement-small,.gridelement-medium {
    vertical-align:top;
    display: inline-block;
    padding: 1.5%;
    margin: 1%;
}

@media only screen and (max-width: 600px) {
    /* For mobile: */
    .gridelement-small,.gridelement-medium {
        width: 100%;
    }
}

@media only screen and (min-width: 600px) {
    /* For tablets: */

    .gridelement-small,.gridelement-medium {
        width: 25%;
    }
}

@media only screen and (min-width: 768px) {
    /* For desktop: */

    .gridelement-small {
        width: 14%;
    }

    .gridelement-medium {
        width: 28%;
    }
}