layout.html

<div class="hiddenWidgetsDiv">
    <!-- widgets in this container are hidden in the UI by default -->
    <div class="component-container hiddenWidgetsContainer ibmDndRow wpthemeCol12of12 wpthemeFull" name="ibmHiddenWidgets"></div>
    <div style="clear:both"></div>
</div>
<!-- this layout contains 3 equally size columns -->
<div class="row topMarginDbl">
    <div class="component-container ibmDndColumn col-sm-3" name="left"></div>
    <div class="component-container ibmDndColumn col-sm-6" name="ibmMainContainer"></div>
    <div class="component-container ibmDndColumn col-sm-3" name="right"></div>
</div>