I haven't worked with IE10, (or IE in general very little), but I did have little problems before with codes between various browsers.
For styling, you're bettor off using a CSS sheet and style your Iframe from there and let the browser sort it out then... It got me over the little differences between the browsers reading style attributes defined in tags
<iframe id="test" src="" frameborder="0" class="Iframe1" />
and in your CSS file: