[UI] Fix whitespace being applied to div instead of p (#9968)

* fix large line breaks

* fix ascii art posts

app/javascript/styles/mastodon/components.scss

@@ -638,7 +638,6 @@
   font-weight: 400;
   overflow: hidden;
   text-overflow: ellipsis;
-  white-space: pre-wrap;
   padding-top: 2px;
   color: $primary-text-color;
 
@@ -662,6 +661,7 @@
 
   p {
     margin-bottom: 20px;
+    white-space: pre-wrap;
 
     &:last-child {
       margin-bottom: 0;