Je veux que mon site s'adapte a tous les resolution d'ecran

.threeCols {   /* gère l'affichage bloc de texte sur deux colonnes */
    -webkit-column-count: 3;
    -webkit-column-rule: 1px dotted #b0b0b0;
    -webkit-column-gap: 16px;
    -moz-column-count: 3;
    -moz-column-rule: 1px dotted #b0b0b0;
    -moz-column-gap: 16px;
    column-count: 3;
    column-rule: 1px dotted #b0b0b0;
    column-gap: 16px;
    padding-bottom: 6px;
    border-bottom: 1px dotted #7f7f7f;
    margin-bottom: 12px;
    margin-top: 6px;
}

@media only screen and (max-width: 1920px) {
    .threeCols {
        -webkit-column-count: 4;
        -moz-column-count: 4;
        column-count: 4;
    }
}

@media only screen and (max-width: 1280px) {
    .threeCols {
        -webkit-column-count: 3;
        -moz-column-count: 3;
        column-count: 3;
    }
}

@media only screen and (max-width: 800px) {
    .threeCols {
        -webkit-column-count: 2;
        -moz-column-count: 2;
        column-count: 2;
    }
}

@media only screen and (max-width: 600px) {
    .threeCols {
        -webkit-column-count: 1;
        -moz-column-count: 1;
        column-count: 1;
    }
}

.twoCols section, .threeCols section {
    display: inline-block;
} 

<div class="theeCols">
 ............
</div>