una/template/layout_3_columns.html

<!-- layout 3 columns [ start ] -->
<div class="bx-layout-wrapper bx-layout-3-columns">
    <div class="bx-layout-row bx-clearfix">
        <div class="bx-layout-col bx-layout-3-columns-column1">
            <div class="bx-layout-cell bx-def-padding-sec-right" id="bx-layout-cell-1">
                __cell_1__
            </div>
        </div>
        <div class="bx-layout-col bx-layout-3-columns-column2">
            <div class="bx-layout-cell bx-def-padding-sec-right bx-def-padding-sec-left" id="bx-layout-cell-2">
                __cell_2__
            </div>
        </div>
        <div class="bx-layout-col bx-layout-3-columns-column3">
            <div class="bx-layout-cell bx-def-padding-sec-left" id="bx-layout-cell-3">
                __cell_3__
            </div>
        </div>
    </div>
</div>
<!-- layout 3 columns [  end  ] -->