MC-15238: Live edit in Safari and Firefox puts caret at start of field after typing

- Resolved firefox cursor in slide button not visible in inline edit on new slides

Author: Hwashiang Yu

app/code/Magento/PageBuilder/view/adminhtml/web/css/source/content-type/slide/_default.less

@@ -36,6 +36,7 @@
 
         span[contenteditable=true] {
             display: block;
+            overflow: hidden;
         }
     }