Style guide: Fix empty state

ts/components/conversation/media-gallery/EmptyState.md

@@ -1,11 +1,29 @@
+### Media Empty State
+
 ```js
-<div style={{ position: 'relative', width: '100%', height: 300 }}>
+<div
+  style={{
+    display: 'flex',
+    position: 'relative',
+    width: '100%',
+    height: 300,
+  }}
+>
   <EmptyState label="You have no attachments with media" />
 </div>
 ```
 
+### Documents Empty State
+
 ```js
-<div style={{ position: 'relative', width: '100%', height: 500 }}>
+<div
+  style={{
+    display: 'flex',
+    position: 'relative',
+    width: '100%',
+    height: 500,
+  }}
+>
   <EmptyState label="You have no documents with media" />
 </div>
 ```