Dark theme: fix header's right control's width

The right control has a fixed width, and so when the dark theme button
is added there, it exceeds this width and overlaps the search bar. This
fixes it.

Change-Id: I9a0ee1082253a3d13d071b5ecacb0c6ab08fb68b
diff --git a/src/injections/ccdarktheme.css b/src/injections/ccdarktheme.css
index 905a6d6..9261e16 100644
--- a/src/injections/ccdarktheme.css
+++ b/src/injections/ccdarktheme.css
@@ -56,6 +56,11 @@
   color: rgba(255, 255, 255, .87)!important;
 }
 
+.material-content > header .right-control {
+  width: auto!important;
+  max-width: none!important;
+}
+
 .material-content > header .bell.mixin {
   fill: rgba(255, 255, 255, .87)!important;
 }