You have to publish the code. Are you using 2 column layout from Kentico or something custom?
Kentico 2 column layout looks like:
<div>
<cms:CMSWebPartZone ZoneID="zoneA" runat="server" />
</div>
<div style="width: 100%;">
<div style="width: 50%; float: left;">
<cms:CMSWebPartZone ZoneID="zoneB" runat="server" />
</div>
<div style="width: 50%; float: right;">
<cms:CMSWebPartZone ZoneID="zoneC" runat="server" />
</div>
</div>
<div style="clear: both">
<cms:CMSWebPartZone ZoneID="zoneD" runat="server" />
</div>
If you insert in zones B and C your editable text web part - they will stretch to the column width.