Comment 2 for bug 452259

There is a workaround, but it is so awful you might want to avert your eyes before looking at it:

    <tal:block define="logo webhelpers/sector_logo" condition="python:logo">
      <tal:pain replace="structure string:&lt;"/>style type="text/css"<tal:pain replace="structure string:&gt;"/>
        #navigation li#home {
          background: url(<tal:block replace="logo"/>) no-repeat;
        }
      <tal:pain replace="structure string:&lt;"/>/style<tal:pain replace="structure string:&gt;"/>
    </tal:block>

As a final note I'ld like to add that chameleon.zpt does not suffer from this problem.