[SalesForce] Constrain VF page to fit within width of dashboard component

I'm trying to format a visualforce page so that it can render correctly in a dashboard element. It's just an rss feed, but the column width is too great. I'd like to limit it's width so that it is completely viewable from the dashboard component.

Here is the VF source:

<apex:page showHeader="false" controller="gAlertCntrl">
    <apex:pageBlock >
        <apex:pageBlockTable value="{!result}" var="alert" columnsWidth="50%">
            <apex:column>
                <b><apex:outputText value="{!alert.Title__c}" escape="false" /></b>
                <br />
                <apex:outputText value="{!alert.Content__c}" escape="false"/>
                <br />
                <em><apex:outputText value="{!alert.Published__c}"/></em>
                <br />
                <a href="{!alert.link__c}" target='_blank'>{!alert.link__c}</a>
                <hr />
            </apex:column>
        </apex:pageBlockTable>
    </apex:pageBlock> 
</apex:page>

I've tried using 'columnsWidth':

<apex:pageBlockTable value="{!result}" var="alert" columnsWidth="50%">

I've tried width:

<apex:pageBlockTable value="{!result}" var="alert" width="50%">

I've also tried both of those values in px instead of %.

I've tried putting the width into the column element:

<apex:column width="50px">

My table still spans beyond the edge of the screen. How can I constrain the width to fit inside a "wide" sized dashboard component?

Thanks all!

Zac