fix sidebar styling on mobile (#1194)

Related To
https://github.com/RaspberryPiFoundation/digital-editor-issues/issues/419


## Bug
<img width="319" alt="image"
src="https://github.com/user-attachments/assets/81f65dbf-33cb-4558-a8ca-7f7d302688ac"
/>

---------

Co-authored-by: Conor <conor.riches@raspberrypi.org>
Co-authored-by: Lois Wells <88904316+loiswells97@users.noreply.github.com>

Author: 3 people

CHANGELOG.md

@@ -10,6 +10,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 - Fake translation for stress testing (#1206)
 
+### Fixed
+- Styling issue on sidebar on mobile (#1194)
+
 ## [0.30.0] - 2025-04-15
 
 ### Added

src/assets/stylesheets/Sidebar.scss

@@ -10,8 +10,13 @@
 }
 
 .sidebar--mobile {
+  block-size: 100%;
   inline-size: 100%;
   overflow-y: hidden;
+
+  .react-tabs .react-tabs__tab-list {
+    flex: unset;
+  }
 }
 
 .editor-logo {