How do I make my layout firefox compatible? Options

[j-kw0n]

My friend made my layout for me & she's busy and sorta uh disappeared so I don't know who to ask about this.

The layout she made is IE compatible but I don't use IE and I'm pretty sure a lot of people I know don't, so is there a way to do something to the CSS to make it firefox compatible? The only weird thing the layout does on Firefox is that the header image is all the way on the left side when it's suppose to be centered :/

please help me TT_TT thank you~


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ALSO, kind of off topic but i didn't wanna make another thread to flood the forum. I want to change my friend locked icon and replace the old one with a new one but for some reason it won't work ):
Also my LJ user icon that my friend made works and you can see it but the original default one is right next to it as well.. how can I get rid of it?