Код:
@namespace url(http://www.w3.org/1999/xhtml);@-moz-document domain("rpgmaker.su"){html{background:#000 url(http://i5.pixs.ru/storage/3/2/4/bggssfinal_5873237_7184324.jpg) no-repeat!important;background-size:100%!important}.above_body{text-align:center!important;background:transparent!important;background:url(http://i5.pixs.ru/storage/6/1/3/logopng_4070116_7183613.png) no-repeat center top!important;background-size:450px!important}.logo-image{float:none!important;padding:0!important;opacity:0!important}.button,input[name="sa"],.navpopupmenu.popupmenu.nohovermenu a.popupctrl,.navpopupmenu.popupmenu.nohovermenu a.textcontrol,.toolsmenu,.toplinks form input.loginbutton,.newcontent_textcontrol,dd.userprof_moduleinactive,.navtabs li a.navtab,dd.userprof_module,.navtabs li.selected a.navtab,a.textcontrol{background:-moz-linear-gradient(top,#555 48%,#333 49%,#000 85%,#333)!important;background:-webkit-linear-gradient(top,#555 48%,#333 49%,#000 85%,#333)!important;box-shadow:1px 1px 3px #000!important;border:1px solid #000!important}.button:hover,input[name="sa"]:hover,.navpopupmenu.popupmenu.nohovermenu a.textcontrol:hover,.toplinks form input.loginbutton:hover,.newcontent_textcontrol:hover,dd.userprof_moduleinactive:hover,.navtabs li a.navtab:hover,dd.userprof_module:hover,.navtabs li.selected a.navtab:hover,a.textcontrol:hover,.postfoot a:hover{border:1px solid hsla(208,44%,63%,.8)!important;box-shadow:0 0 14px hsla(208,44%,63%,.6),0 0 15px hsla(208,44%,63%,.4) inset!important}.navtabs li a.navtab:hover{color:#fff!important}.navtabs li.selected a.navtab{color:#fff!important}.blockhead,#searchtypeswitcher,.searchlisthead,.navtabs,.navbar,.footer,span.forumtitle,span.forumthreadpost,span.forumlastpost,.forumhead,.toplinks{background:-moz-linear-gradient(top,hsl(208,44%,33%) 48%,hsl(208,44%,15%) 49%,hsl(208,35%,7%) 85%,hsl(208,40%,33%))!important;background:-webkit-linear-gradient(top,hsl(208,44%,33%) 48%,hsl(208,44%,15%) 49%,hsl(208,35%,7%) 85%,hsl(208,40%,33%))!important;box-shadow:1px 1px 3px #000!important}.time{color:#aaa!important}#footer_morecopyright{color:#ddd!important;text-shadow:1px 1px 8px #DDD!important}.popupbody{border:2px solid rgba(0,0,0,.8)!important}.forumrow,#pollinfo,.bloglist,#below_unread,.forumhead,.announcerow,#wgo,.forum_info_subblock,.blockbody,.threadlist,li[id^="post_thanks_box_"],.userprof_headers,.notices li,.blockfoot,.blocksubfoot,#sidebar_container.member_summary,ul.userlist_showavatars li,li.userprof_content,.toplinks ul.isuser,.toplinks ul.nouser,.vbseo_share_body,#threadlist,li[id^="thread_"]{box-shadow:-2px 2px 2px rgba(0,0,0,.7)!important}.popupbody,.vbseo_share_body,#vbseo-likes.vbseo-likes-active,#vbseo-likes.vbseo-likes-tpreload,.vbseo-likes-container{box-shadow:0 4px 7px #000!important}a.popupctrl.active,a.popupctrl:hover,.toplinks ul.isuser li a:hover,#logindetails,.toplinks ul.nouser li a,.postfoot *{background-color:transparent!important}a.popupctrl.active,a.popupctrl:hover,.toplinks ul.isuser li a:hover,.breadcrumb .navbit a:hover{box-shadow:0 0 1px 1px hsl(208,44%,63%) inset,0 0 15px hsla(208,44%,63%,.4) inset!important}input.button{background:#e9e9e9 url(http://rpgmaker.su/images/gradients/generic_button.png) repeat-x top left!important}input.button:hover{box-shadow:none!important}.blockfoot{box-shadow:none!important}.polltitle{color:#fff!important}#pollinfo>.blockhead>h2{color:white!important;padding-left:10px!important}#pollinfo>.block>.blockhead>h2{color:white!important;padding-left:10px!important}#pollinfo>.blockhead>.stats>.totalvotes{color:white!important}#pollinfo>.blockhead>.stats>dd>.totalvotes{color:white!important}span.ctrlcontainer,a.textcontrol,#threadtools>h6>a#yui-gen9,a#yui-gen11,a#yui-gen12,a#yui-gen13,a#yui-gen14,a#yui-gen15,a#yui-gen16,a#yui-gen18{color:white!important;text-shadow:1px 1px 8px #DDD!important}#pagination_bottom>#yui-gen11>.popupspan>a#yui-gen13{color:#417394!important}#pagination_bottom>#yui-gen11>span>a#yui-gen13{color:#417394!important}#pagetitle>h1>span.forumtitle{background:transparent!important}.friends_mini>.blocksubhead>a.textcontrol.imagecontrol{background:transparent!important}.tabslight>dd.userprof_moduleinactive>a{color:white!important}div.blog_date>div.popupmenu>a.username>strong{color:#417394!important}.blog_date>.popupmenu.memberaction>.username.online.popupctrl>strong{color:blue!important}}
4) Добавляем скопированный код в Stylish. Для этого открываем страницу "Управление дополнениями" (Меню - Инструменты - Дополнения или ctrl+shift+A), выбираем вкладку "Стили", нажимаем "Создать новый стиль". Название даём любое. В самое большое поле вставляем скопированный ранее код и жмём сохранить.