Use more toned colors for selected line (#11493)

Co-authored-by: zeripath <art27@cantab.net>

web_src/less/_base.less

@@ -1177,7 +1177,7 @@ i.icon.centerlock {
     }
 
     .lines-code .active {
-        background: #fff866;
+        background: #fff6af;
     }
 }
 

web_src/less/themes/theme-arc-green.less

@@ -1138,7 +1138,7 @@ td.blob-excerpt {
 }
 
 .lines-code .code-view .active {
-    background: #554a00;
+    background: #534d1b;
 }
 
 a.ui.label:hover,