Merge pull request #23170 from overleaf/mj-ide-resize-handle-bg

[web] Override resize handle background colour in editor redesign

GitOrigin-RevId: b429dc5d0f0369c7bd54f29b5e499411ac9398d6

services/web/frontend/stylesheets/bootstrap-5/pages/editor/ide-redesign.scss

@@ -7,6 +7,8 @@
 }
 
 .ide-redesign-main {
+  --editor-resizer-bg-color: var(--bg-light-tertiary);
+
   height: 100%;
   display: flex;
   flex-direction: column;