The CKEditor is used as WYSIWYG in In-Portal. One of the features of it is ability to predefine styles so that later user can apply them easily by using "Styles" dropdown:
The problem is that dropdown itself doesn't resize to ensure 100% of styled text fragment is visible (on image above complete text says "Large header", but only "Large" word is visible).
Solution
Change width/height of Styles dropdown (CSS selector: "div.cke_combopanel__styles") to 200x300 (was 150x170).