frontend/src/features/workspace/OutlinerBlock.tsx

@@ -344,11 +344,19 @@ export const OutlinerBlock: React.FC<OutlinerBlockProps> = ({
       return;
     }
 
-    // 2. Enter (without Shift) -> Create new block on same level
+    // 2. Enter (without Shift) -> If block is completely empty and level > minLevel, outdent (Shift+Tab behaviour), otherwise create new block below
     if (e.key === 'Enter' && !e.shiftKey && block.type !== 'code') {
       e.preventDefault();
       e.stopPropagation();
       setSlashSearch(null);
+
+      const minLevel = levelOffset || 0;
+      if (localContent === '' && Math.max(0, block.level || 0) > minLevel) {
+        flushDebounce(localContent);
+        onIndentBlockRef.current(block.id, -1);
+        return;
+      }
+
       flushDebounce(localContent);
       onCreateBlockBelowRef.current(block.id, localContent);
       return;