Dark theme: fix right controls' dialogs position

Allowing the right controls div to have unlimited width, in large
screens the dialogs which are shown when clicking the buttons aren't
shown below the buttons but displaced to the left.

This change sets a fixed maximum width so the dialogs are shown
correctly but there is still space for all the buttons.

Change-Id: I0499662f0accc5d3c0423d5e077d69ccceb2f4e4
diff --git a/src/injections/ccdarktheme.css b/src/injections/ccdarktheme.css
index 9261e16..1614b43 100644
--- a/src/injections/ccdarktheme.css
+++ b/src/injections/ccdarktheme.css
@@ -58,7 +58,7 @@
 
 .material-content > header .right-control {
   width: auto!important;
-  max-width: none!important;
+  max-width: 252px!important;
 }
 
 .material-content > header .bell.mixin {