Chaotic soul slight modification - need help

[JohnJohn]

I've been trying to adapt it a bit with more or less success and i'd like to know if someone can gave me tips if not answers because to be honest, even if i have a bit more than basics understanding of web design, it took me far too much time to achieve, when it works, good results.

So firstly i need to change the width of sidebar while extending the width of main content. Something like 50 pixels less for menu bar, and so 50 pixels more for mainframe. This would allow for thumbnails of greater size while letting some space around them. And anyway, there is too much space lost in sidebar.
I managed to find how to reduce sidebar width, but absolutely not how to extend main content width, thus breaking the layout each time ...

URL of my gallery : http://johnmagnus.free.fr/entropia/copper/

Thx by advance for your help

[Gizmo]

In the style.css

find

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#content { float: left; font-size: 1.1em; width: 617px; }
replace with

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#content { float: left; font-size: 1.1em; width: 667px; }

and find

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#sidebar { border-left: 0; float: right; width: 200px; }
replace with

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#sidebar { border-left: 0; float: right; width: 150px; }

Then drop this new attached content_bkg.gif into the image folder to replace the current one.

[JohnJohn]

It works

Thx a lot

so all my problem was in fact the background img. Because of the border effect color of this image, I was thinking it was another table somewhere who broke the layout ... 

Really thank you