allargare margini forum

Ciao a tutti. doveri allargare i margini del forum, ho letto in giro come si fa ma provando non funziona. uso lo stile prosilver Special Edition e questo e una parte del tema il tema:

/* phpBB3 Style Sheet
--------------------------------------------------------------
Style name: prosilver Special Edition
Based on style: prosilver (the default phpBB 3.0.x style)
Original author: Tom Beddard ( http://www.subblue.com/ )
Modified by: phpBB Group ( http://www.phpbb.com/ )
--------------------------------------------------------------
*/

/* General Markup Styles
---------------------------------------- */

* {
/* Reset browsers default margin, padding and font sizes */
margin: 0;
padding: 0;
}

html {
font-size: 100%;
/* Always show a scrollbar for short pages - stops the jump when the scrollbar appears. non-IE browsers */
height: 101%;
}

body {
/* Text-Sizing with ems: http://www.clagnut.com/blog/348/ */
font-family: Verdana, Helvetica, Arial, sans-serif;
color: #828282;
background-color: #FFFFFF;
/*font-size: 62.5%; This sets the default font size to be equivalent to 10px */
font-size: 10px;
margin: 0;
padding: 27px 0;
}

h1 {
/* Forum name */
font-family: "Trebuchet MS", Arial, Helvetica, sans-serif;
margin-right: 200px;
color: #FFFFFF;
margin-top: 15px;
font-weight: bold;
font-size: 2em;
}

h2 {
/* Forum header titles */
font-family: "Trebuchet MS", Arial, Helvetica, sans-serif;
font-weight: normal;
color: #3f3f3f;
font-size: 2em;
margin: 0.8em 0 0.2em 0;
}

h2.solo {
margin-bottom: 1em;
}

h3 {
/* Sub-headers (also used as post headers, but defined later) */
font-family: Arial, Helvetica, sans-serif;
font-weight: bold;
text-transform: uppercase;
border-bottom: 1px solid #CCCCCC;
margin-bottom: 3px;
padding-bottom: 2px;
font-size: 1.05em;
color: #989898;
margin-top: 20px;
}

h4 {
/* Forum and topic list titles */
font-family: "Trebuchet MS", Verdana, Helvetica, Arial, Sans-serif;
font-size: 1.3em;
}

p {
line-height: 1.3em;
font-size: 1.1em;
margin-bottom: 1.5em;
}

img {
border-width: 0;
}

hr {
/* Also see tweaks.css */
border: 0 none #FFFFFF;
border-top: 1px solid #CCCCCC;
height: 1px;
margin: 5px 0;
display: block;
clear: both;
}

hr.dashed {
border-top: 1px dashed #CCCCCC;
margin: 10px 0;
}

hr.divider {
display: none;
}

p.right {
text-align: right;
}

/* Border
---------------------------------------- */
.border-left {
background: url("{T_THEME_PATH}/images/border_left.gif") #FFFFFF repeat-y 0 0;
}

.border-right {
background: url("{T_THEME_PATH}/images/border_right.gif") repeat-y 100% 0;
}

.border-top {
background: url("{T_THEME_PATH}/images/border_top.gif") repeat-x 0 0;
}

.border-top-left {
background: url("{T_THEME_PATH}/images/border_top_left.gif") no-repeat 0 0;
}

.border-top-right {
background: url("{T_THEME_PATH}/images/border_top_right.gif") no-repeat 100% 0;
}

.border-bottom {
background: url("{T_THEME_PATH}/images/border_bottom2.gif") repeat-x 0 100%;
}

.border-left, .border-right, .border-top, .border-top-left, .border-top-right, .border-bottom { width: 100%;}

.border-bottom span {
background: url("{T_THEME_PATH}/images/border_bottom.gif") no-repeat 0 0;
display: block;
height: 18px;
}

.border-bottom span span {
background-position: 100% -18px;
}

.inside {
padding: 17px 27px 10px 27px;
}

/* Main blocks
---------------------------------------- */
#wrap {
padding: 0 20px;
min-width: 650px;
width: 900px;
margin: 0 auto;
}

#simple-wrap {
padding: 6px 10px;
}

#page-body {
margin: 4px 0;
clear: both;
}

#page-footer {
clear: both;
}

#page-footer h3 {
margin-top: 20px;
}

#logo {
float: left;
width: auto;
padding: 10px 13px 0 10px;
}

a#logo:hover {
text-decoration: none;
}

/* Search box
--------------------------------------------- */
#search-box {
color: #FFFFFF;
position: relative;
margin-top: 30px;
margin-right: 5px;
display: block;
float: right;
text-align: right;
white-space: nowrap; /* For Opera */
}

#search-box #keywords {
width: 95px;
background-color: #FFF;
}

#search-box input {
border: 1px solid #b0b0b0;
}

/* .button1 style defined later, just a few tweaks for the search button version */
#search-box input.button1 {
padding: 1px 5px;
}

#search-box li {
text-align: right;
margin-top: 4px;
}

#search-box img {
vertical-align: middle;
margin-right: 3px;
}

/* Site description and logo */
#site-description {
float: left;
width: 70%;
}

#site-description h1 {
margin-right: 0;
}

/* Round cornered boxes and backgrounds
---------------------------------------- */
.headerbar {
background: #ebebeb none repeat-x 0 0;
color: #FFFFFF;
margin-bottom: 4px;
padding: 0 5px;
}
........................

che parte devo modificare?
Grazie:=)::=):