Issue with "Show more" feature

I’m trying to add the " show more" feature as shown in here:
The issue I’m facing is Font and format changes automatically after I press to “show more” .

PFA, attached snapshots.
If you are following that tutorial, then nothing should change when you click on the show more button.

Looking at your page layout, you might be better doing this sort of double collapse design from Nayeli (Code Queen) as shown here.

Thank you, perfectly suits my requirement

Thanks a lot for the video. I have a small issue, screen size does not get adjusted automatically after the collapse and expand. Am I missing something while coding? Kindly let me know.