diff --git a/lib/tpl/dokuwiki/css/structure.less b/lib/tpl/dokuwiki/css/structure.less
index 3f22f57e399f666d3e3a681c56f9d55974564450..f24440f0804e22954f579762fe1fbf9ce5190d11 100644
--- a/lib/tpl/dokuwiki/css/structure.less
+++ b/lib/tpl/dokuwiki/css/structure.less
@@ -67,14 +67,14 @@ body {
 
 .showSidebar #dokuwiki__content {
     float: right;
-    margin-left: -@ini_sidebar_width;
+    margin-left: (-1 * @ini_sidebar_width);
     width: 100%;
 }
 
 [dir=rtl] .showSidebar #dokuwiki__content {
     float: left;
     margin-left: 0;
-    margin-right: -@ini_sidebar_width;
+    margin-right: (-1 * @ini_sidebar_width);
 }
 
 .showSidebar #dokuwiki__content > .pad {