refactor: migrate some styling features to the new architecture

Again, by using StylesheetScript we also get dynamic styles for free.

Bug: twpowertools:176, twpowertools:61
Change-Id: I8c660f8b9cddaf56b3a29c8d07d48d070ee2cd34
diff --git a/templates/manifest.gjson b/templates/manifest.gjson
index 2f3f4cf..d183096 100644
--- a/templates/manifest.gjson
+++ b/templates/manifest.gjson
@@ -119,6 +119,9 @@
         "css/thread_page_design_warning.css",
         "css/thread_toolbar.css",
         "css/flatten_threads.css",
+        "css/fixed_toolbar.css",
+        "css/increase_contrast.css",
+        "css/sticky_sidebar_headers.css",
 
         "communityConsoleMain.bundle.js.map",
         "communityConsoleStart.bundle.js.map",