How To Find A Css Class

Im looking to alter the width of an element and can see it in firebug as 796, so when I change it to try it works, but I can see what the class is to chnage as it just says, "element" on the right of the screen shot.

in this case how do I detremine the css class to add to the editor. I have tried copying some items from the left but changes wont work



An 'element' class indicates that a 'styles' attribute was used for the object. Hence you would have to change the source code.

Most possibly this width is calculated dynamically by javascript depending on screen resolution. If not, this value can be find in the corresponding template