请教宽屏修改

我想把dz默认模版宽屏改成1200，在这个文件了改widthauto.css，要改那里那，麻烦指导一下。

/* ----------------------------------
Self-adaption Width CSS file for Discuz! X
(C) Comsenz Inc.
http://www.comsenz.com
Created & Modified by Pony.
---------------------------------- */

.wp { width: 98%; }
        #hd .wp, #wp { min-width: 960px; }

.ct2 { margin-right: 235px; }
        .ct2 .sd { margin-right: -235px; }
                .ie7 .ct2 .sd { margin-left: 15px; }
                .ie6 .ct2 .sd { padding-left: 15px; position: relative; }
        .ct2 .mn { width: 100%; }

.ct2 #chart, .ct2 #an { margin-right: -235px; }
        .ie6 .ct2 #chart, .ie6 .ct2 #an { position: relative; }

.ct2_a { padding-left: 150px; }
        .ct2_a .appl { margin-left: -150px; }
                .ie6 .ct2_a .appl { position: relative; display: inline; }
        .ct2_a .mn { width: 99%; }
        #nv_userapp .ct2_a .mn, .ct2_a_r .mn { width: 99%; }

.ct3_a { padding: 0 240px 0 160px; }
        .ct3_a .appl { margin-left: -160px; }
                .ie6 .ct3_a .appl, .ie6 .ct3_a .sd { display: inline; }
        .ct3_a .sd { margin-right: -240px; }
        .ct3_a .mn { margin: 0; width: 100%; }

#nv, #mu { border-left: 1px solid {COMMONBORDER}; border-right: 1px solid {COMMONBORDER}; }

#nv { background-repeat: repeat-x; background-position: 0 -33px; }

#mu ul { border-bottom: 1px solid {COMMONBORDER}; background-image: none; background-color: {COMMONBG}; }

.pg_post .ct2_a { margin-left: 0; padding-left: 0; }
        .pg_post .ct2_a .appl { margin-left: 0; background: none; }
.pg_modcp .ct2_a, .pg_announcement .ct2_a { border: none; }
        .pg_modcp .ct2_a .mn, .pg_announcement .ct2_a .mn { margin-right: 0; padding-top: 0; }

.tdats .tdat { width: 20%; }
.tdats .tfxf { width: 79.5%; }
.tdats .tfx, .tdats .tb, .tscr { width: 39.5%; }
        .tscr .tdat, .tscr .tdat th, .tscr .tdat td { width: 100%; }

.widthauto #toptb #diy-tg_menu { margin: -7px 0 0 -1px; }
.widthauto .switchwidth { background-position: 100% -18px; }
.widthauto .switchwidth:hover { background: url({IMGDIR}/switch_width.png) no-repeat 100% -54px; }