Hi Yesid,
Now I finally know what it’s all about 
You’re right. Currently, it doesn’t work because the icon control (and some others) is not a CSS control. Since we have to rewrite the whole control, we can’t implement a “simple fix” but will change that in the future.
Until then, you can use a simple workaround: set a width/height of 100% for your icon and add the desired widths/heights in the Style > Layout tab, or use custom CSS instead.
Best regards,
timmse