If you want a good suggestion: please avoid doing this kind of things, why wouldn't you let people to right click with mouse and wouldn't allow them to copy the whole content? I know that you don't want to show them your html source, don't want your content to be stolen and used elsewhere, but if you don't want that, when keep it for yourself I guess, why would you want to publish it then?
I know that when the first websites appeared, they were quite simple, just simple html tags, people wouldn't even care about somebody looking at the source, maybe they should have done something in the beginning by thinking that the future of html will be much more complicated and people will have their own design, but as I said, stay with my suggestion about not worrying about this kind of things, if the browser can show the source, that means that the guy who is using the browser also can see the source one or another way!
Be happy, that noone can take your server side scripting/programming code like asp, php..

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