feat: extract common flatten thread styles

These styles will also be used for the future bulk report replies
feature.

Bug: twpowertools:192
Change-Id: I6a6a636cbe4708b1d733e11c64c84e3c26d01a9d
diff --git a/src/entryPoints/communityConsole/contentScripts/main.ts b/src/entryPoints/communityConsole/contentScripts/main.ts
index 16bd30f..7eda953 100644
--- a/src/entryPoints/communityConsole/contentScripts/main.ts
+++ b/src/entryPoints/communityConsole/contentScripts/main.ts
@@ -47,7 +47,6 @@
 import FlattenThreadsReaddReplyBtnHandler from '../../../features/flattenThreads/presentation/nodeWatcherHandlers/readdReplyBtn.handler';
 import FlattenThreadsReplyBtnHandler from '../../../features/flattenThreads/presentation/nodeWatcherHandlers/replyBtn.handler';
 import FlattenThreads from '../../../features/flattenThreads/core/flattenThreads';
-import FlattenThreadsStylesScript from '../../../features/flattenThreads/presentation/scripts/styles.script';
 import FixedToolbarStylesScript from '../../../features/fixedToolbar/presentation/scripts/styles.script';
 import EnhancedAnnouncementsDotStylesScript from '../../../features/enhancedAnnouncementsDot/presentation/scripts/styles.script';
 import ImageMaxHeightStylesScript from '../../../features/imageMaxHeight/presentation/scripts/styles.script';
@@ -182,7 +181,6 @@
         new CCExtraInfoStylesScript(),
         new EnhancedAnnouncementsDotStylesScript(),
         new FixedToolbarStylesScript(),
-        new FlattenThreadsStylesScript(),
         new ImageMaxHeightStylesScript(),
         new IncreaseContrastStylesScript(),
         new RepositionExpandThreadStylesScript(),
diff --git a/src/features/flattenThreads/presentation/scripts/styles.script.ts b/src/features/flattenThreads/presentation/scripts/styles.script.ts
deleted file mode 100644
index 338adb2..0000000
--- a/src/features/flattenThreads/presentation/scripts/styles.script.ts
+++ /dev/null
@@ -1,12 +0,0 @@
-import Script from '../../../../common/architecture/scripts/Script';
-import { injectStylesheet } from '../../../../common/contentScriptsUtils';
-
-export default class FlattenThreadsStylesScript extends Script {
-  page: never;
-  environment: never;
-  runPhase: never;
-
-  execute() {
-    injectStylesheet(chrome.runtime.getURL('css/flatten_threads.css'));
-  }
-}
diff --git a/src/static/css/common/console.css b/src/static/css/common/console.css
index 20cb248..68724b4 100644
--- a/src/static/css/common/console.css
+++ b/src/static/css/common/console.css
@@ -160,3 +160,25 @@
   width: auto!important;
   max-width: 252px!important;
 }
+
+/*
+ * This is needed in order to be able to inject further controls to the message
+ * actions section.
+ *
+ * It is feature gated in case this can break this component in the future. In
+ * that case, only users who have enabled one of the specified features will
+ * experience the breakage.
+ **/
+body.TWPT-flattenthreads-enabled {
+  ec-thread sc-tailwind-thread-message-message-list sc-tailwind-thread-message-message-actions {
+    display: flex;
+    flex-direction: row;
+    align-items: center;
+    gap: 0.75rem;
+    margin-top: 1rem;
+    > :not(bulk-report-controls) {
+      margin: 0!important;
+      padding: 0!important;
+    }
+  }
+}
diff --git a/src/static/css/flatten_threads.css b/src/static/css/flatten_threads.css
deleted file mode 100644
index 8a06ef3..0000000
--- a/src/static/css/flatten_threads.css
+++ /dev/null
@@ -1,12 +0,0 @@
-body.TWPT-flattenthreads-enabled ec-thread sc-tailwind-thread-message-message-list:last-child sc-tailwind-thread-message-message-actions {
-  display: flex;
-  flex-direction: row;
-  align-items: center;
-  gap: 0.75rem;
-  margin-top: 1rem;
-}
-
-body.TWPT-flattenthreads-enabled ec-thread sc-tailwind-thread-message-message-list:last-child sc-tailwind-thread-message-message-actions > * {
-  margin: 0;
-  padding: 0;
-}
diff --git a/templates/manifest.gjson b/templates/manifest.gjson
index d183096..865c12b 100644
--- a/templates/manifest.gjson
+++ b/templates/manifest.gjson
@@ -118,7 +118,6 @@
         "css/ui_spacing/twbasic.css",
         "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",