Corporate Theme (Changing width)

Hi,

I would like to change the width of the corporate theme from 950px to 1000px. I found the appropriate file and changed it to

/* grid.css */
.container {width:950px;margin:0 auto;}

But after that the theme is not in the center anymore but slides a little bit to the left. I believe that it extended the extra 50px solely caused by a fixed margin right maybe!?

Since there are tons of files (at least to me) I don’t know which one I have to change so it will center the page. Since I believe it must be somewhere in the grid.css I posted the rest of it. I would appreciate if someone has an idea.

/* grid.css */
.container {width:950px;margin:0 auto;}
.showgrid {background:url(src/grid.png);}
body {margin:1.5em 0;}
div.span-1, div.span-2, div.span-3, div.span-4, div.span-5, div.span-6, div.span-7, div.span-8, div.span-9, div.span-10, div.span-11, div.span-12, div.span-13, div.span-14, div.span-15, div.span-16, div.span-17, div.span-18, div.span-19, div.span-20, div.span-21, div.span-22, div.span-23, div.span-24 {float:left;margin-right:10px;}
div.last {margin-right:0;}
.span-1 {width:30px;}
.span-2 {width:70px;}
.span-3 {width:110px;}
.span-4 {width:150px;}
.span-5 {width:190px;}
.span-6 {width:230px;}
.span-7 {width:270px;}
.span-8 {width:310px;}
.span-9 {width:350px;}
.span-10 {width:390px;}
.span-11 {width:430px;}
.span-12 {width:470px;}
.span-13 {width:510px;}
.span-14 {width:550px;}
.span-15 {width:590px;}
.span-16 {width:630px;}
.span-17 {width:670px;}
.span-18 {width:710px;}
.span-19 {width:750px;}
.span-20 {width:790px;}
.span-21 {width:830px;}
.span-22 {width:870px;}
.span-23 {width:910px;}
.span-24, div.span-24 {width:950px;margin:0;}
.append-1 {padding-right:40px;}
.append-2 {padding-right:80px;}
.append-3 {padding-right:120px;}
.append-4 {padding-right:160px;}
.append-5 {padding-right:200px;}
.append-6 {padding-right:240px;}
.append-7 {padding-right:280px;}
.append-8 {padding-right:320px;}
.append-9 {padding-right:360px;}
.append-10 {padding-right:400px;}
.append-11 {padding-right:440px;}
.append-12 {padding-right:480px;}
.append-13 {padding-right:520px;}
.append-14 {padding-right:560px;}
.append-15 {padding-right:600px;}
.append-16 {padding-right:640px;}
.append-17 {padding-right:680px;}
.append-18 {padding-right:720px;}
.append-19 {padding-right:760px;}
.append-20 {padding-right:800px;}
.append-21 {padding-right:840px;}
.append-22 {padding-right:880px;}
.append-23 {padding-right:920px;}
.prepend-1 {padding-left:40px;}
.prepend-2 {padding-left:80px;}
.prepend-3 {padding-left:120px;}
.prepend-4 {padding-left:160px;}
.prepend-5 {padding-left:200px;}
.prepend-6 {padding-left:240px;}
.prepend-7 {padding-left:280px;}
.prepend-8 {padding-left:320px;}
.prepend-9 {padding-left:360px;}
.prepend-10 {padding-left:400px;}
.prepend-11 {padding-left:440px;}
.prepend-12 {padding-left:480px;}
.prepend-13 {padding-left:520px;}
.prepend-14 {padding-left:560px;}
.prepend-15 {padding-left:600px;}
.prepend-16 {padding-left:640px;}
.prepend-17 {padding-left:680px;}
.prepend-18 {padding-left:720px;}
.prepend-19 {padding-left:760px;}
.prepend-20 {padding-left:800px;}
.prepend-21 {padding-left:840px;}
.prepend-22 {padding-left:880px;}
.prepend-23 {padding-left:920px;}
div.border {padding-right:4px;margin-right:5px;border-right:1px solid #eee;}
div.colborder {padding-right:24px;margin-right:25px;border-right:1px solid #eee;}
.pull-1 {margin-left:-40px;}
.pull-2 {margin-left:-80px;}
.pull-3 {margin-left:-120px;}
.pull-4 {margin-left:-160px;}
.pull-5 {margin-left:-200px;}
.pull-6 {margin-left:-240px;}
.pull-7 {margin-left:-280px;}
.pull-8 {margin-left:-320px;}
.pull-9 {margin-left:-360px;}
.pull-10 {margin-left:-400px;}
.pull-11 {margin-left:-440px;}
.pull-12 {margin-left:-480px;}
.pull-13 {margin-left:-520px;}
.pull-14 {margin-left:-560px;}
.pull-15 {margin-left:-600px;}
.pull-16 {margin-left:-640px;}
.pull-17 {margin-left:-680px;}
.pull-18 {margin-left:-720px;}
.pull-19 {margin-left:-760px;}
.pull-20 {margin-left:-800px;}
.pull-21 {margin-left:-840px;}
.pull-22 {margin-left:-880px;}
.pull-23 {margin-left:-920px;}
.pull-24 {margin-left:-960px;}
.pull-1, .pull-2, .pull-3, .pull-4, .pull-5, .pull-6, .pull-7, .pull-8, .pull-9, .pull-10, .pull-11, .pull-12, .pull-13, .pull-14, .pull-15, .pull-16, .pull-17, .pull-18, .pull-19, .pull-20, .pull-21, .pull-22, .pull-23, .pull-24 {float:left;position:relative;}
.push-1 {margin:0 -40px 1.5em 40px;}
.push-2 {margin:0 -80px 1.5em 80px;}
.push-3 {margin:0 -120px 1.5em 120px;}
.push-4 {margin:0 -160px 1.5em 160px;}
.push-5 {margin:0 -200px 1.5em 200px;}
.push-6 {margin:0 -240px 1.5em 240px;}
.push-7 {margin:0 -280px 1.5em 280px;}
.push-8 {margin:0 -320px 1.5em 320px;}
.push-9 {margin:0 -360px 1.5em 360px;}
.push-10 {margin:0 -400px 1.5em 400px;}
.push-11 {margin:0 -440px 1.5em 440px;}
.push-12 {margin:0 -480px 1.5em 480px;}
.push-13 {margin:0 -520px 1.5em 520px;}
.push-14 {margin:0 -560px 1.5em 560px;}
.push-15 {margin:0 -600px 1.5em 600px;}
.push-16 {margin:0 -640px 1.5em 640px;}
.push-17 {margin:0 -680px 1.5em 680px;}
.push-18 {margin:0 -720px 1.5em 720px;}
.push-19 {margin:0 -760px 1.5em 760px;}
.push-20 {margin:0 -800px 1.5em 800px;}
.push-21 {margin:0 -840px 1.5em 840px;}
.push-22 {margin:0 -880px 1.5em 880px;}
.push-23 {margin:0 -920px 1.5em 920px;}
.push-24 {margin:0 -960px 1.5em 960px;}
.push-1, .push-2, .push-3, .push-4, .push-5, .push-6, .push-7, .push-8, .push-9, .push-10, .push-11, .push-12, .push-13, .push-14, .push-15, .push-16, .push-17, .push-18, .push-19, .push-20, .push-21, .push-22, .push-23, .push-24 {float:right;position:relative;}
.box {padding:1.5em;margin-bottom:1.5em;background:#E5ECF9;}
hr {background:#ddd;color:#ddd;clear:both;float:none;width:100%;height:.1em;margin:0 0 1.45em;border:none;}
hr.space {background:#fff;color:#fff;}
.clearfix:after, .container:after {content:".";display:block;height:0;clear:both;visibility:hidden;}
.clearfix, .container {display:inline-block;}
* html .clearfix, * html .container {height:1%;}
.clearfix, .container {display:block;}
.clear {clear:both;}

Thanks you!