Appended content is loaded above button

When using the "button" loading method, my content was being loaded above the button, requiring the user to scroll up to view new content rather than down. It seems this is due to new browser scroll anchoring behavior. The fix was to add the CSS property `overflow-anchor: none;` to the button container.

Start by locating the button loading method and its button container in the plugin. Reproduce the behavior with appended content, then verify that applying the reported overflow-anchor setting prevents the browser from anchoring above the button. Done means new content appears below the button without requiring the user to scroll up.

Written by the indexing model from the issue text.