How to set width of a p:column in a p:dataTable in PrimeFaces 3.0?

I'm using PrimeFaces 3.0-M3 and I have a <p:dataTable> with two columns in it. I want the first column to be fixed at a width of 20px. The other column can use whatever space is left over.

Here are screenshots of what I'm currently getting:

The first <p:column> seems to be ignoring the style setting that should have limited the width. It is sized way too big for the tiny coloured square that is the only content inside it and then the other column is pushed too far to the right.

Here is more of my Facelet code:

<p:dataTable
        id="dataTableExpressions"
        value="#{catconBean.userDefinedExpressionDataModel}"
        var="currentRow"
        emptyMessage="!! EMPTY TABLE MESSAGE !!"
        selection="#{catconBean.userDefinedExpressionToEdit}"
        selectionMode="single">
    <p:ajax 
            event="rowSelect" 
            listener="#{catconBean.onUserDefinedExpressionRowSelect}"
            update=":toolbarForm:catconToolbar" />
    <p:ajax 
            event="rowUnselect" 
            listener="#{catconBean.onUserDefinedExpressionRowUnselect}"
            update=":toolbarForm:catconToolbar" />

    <p:column id="paletteColor" style="width:20px;">
        <h:panelGroup 
                layout="block"
                rendered="#{not empty currentRow.paletteColor}"
                style="width:16px;height:16px;border:thin;border-style:solid;border-color:black;background-color:##{currentRow.paletteColor.RGB};" />
        <h:panelGroup 
                layout="block"
                rendered="#{empty currentRow.paletteColor}"
                style="width:16px;height:16px;border:thin;border-style:dashed;border-color:red;background-color:white;text-align:center;">
            <h:outputTex