css calculation of the width

I got into a math problem

my con开发者_C百科tent box is 700pc wide my hentry (inside content) is 100% wide with padding of 10px

wich make the hentry to be wider that the content resulting and overflow...

Any solution

Here is the page : http://www.equipe94.com

I have firebug and removing the width 100% work, but it send by wordpress so how to overwrite a width:100% with nothing ?

.hentry { width: auto; }

Or this way: If you have a padding of 10px then your inside content box must have a width of

700px - 2 * 10px = 680px