Checkboxlist Font-Size Attribute not functioning with ClientIDMode of AutoID

I have a CheckBoxList within an UpdatePanel with the ClientIDMode set to AutoID. In this mode the Font-Size attribute for the CheckBoxList has no effect. If I switch the ClientIDMode to Static then the Font-Size Attribute works but Async Postback does not. Ive tried using css on the surrounding containers which allows for every change (ex. Font-Weight, Font-Family, etc) but not Font-Size. Im at a loss since I need both the font-size change and Async postback.
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