Update some styles for the Mithril app

less/forum/index.less

@@ -70,7 +70,7 @@
       .box-shadow(2px 2px 6px -2px @fl-shadow-color);
       .transition(left 0.2s);
 
-      &.showing {
+      .pane-showing & {
         left: 0;
       }
       & .container {
@@ -106,7 +106,7 @@
 
 @media @desktop-hd {
   .index-area.paned {
-    .with-pane & {
+    .pane-pinned & {
       left: 0;
       z-index: @zindex-composer - 1;
       .transition(none);
@@ -114,7 +114,7 @@
   }
   // When the pane is pinned, move the other page content inwards
   .global-content, .global-footer {
-    .with-pane & {
+    .has-pane.pane-pinned & {
       margin-left: @index-pane-width;
       & .container {
         max-width: 100%;
@@ -123,7 +123,7 @@
     }
   }
   .global-header .container {
-    .with-pane & {
+    .has-pane.pane-pinned & {
       width: 100%;
     }
   }