css: fix fluid container for spilt diff view

public/css/gogs.css

@@ -4,14 +4,14 @@
   display: inline-block;
   background-size: contain;
 }
-body {
+body:not(.full-width) {
   font-family: "PingFang SC", "Helvetica Neue", "Microsoft YaHei", Arial, Helvetica, sans-serif !important;
   background-color: #fff;
   overflow-y: scroll;
   overflow-x: auto;
   min-width: 1020px;
 }
-.ui.container {
+.ui.container:not(.fluid) {
   width: 980px !important;
 }
 h1,

public/less/_base.less

@@ -1,13 +1,13 @@
 @footer-margin: 40px;
 
-body {
+body:not(.full-width) {
 	font-family: "PingFang SC", "Helvetica Neue", "Microsoft YaHei", Arial, Helvetica, sans-serif !important;
 	background-color: #fff;
 	overflow-y: scroll;
 	overflow-x: auto;
 	min-width: 1020px;
 }
-.ui.container {
+.ui.container:not(.fluid) {
 	width: 980px !important;
 }
 h1, h2, h3, h4, h5,