Thanks, Joy, for your prompt reply. Then I will just use Gutenberg to build up some buttons and columns to function as headers and footers. I’ve searched the web for a solution. Thanks for giving me a guiding advice!
I added a “more” block to my page, but it doesn’t work. It still shows the full page. Don’t know why the more block fails.
And why the “post name” format of permalink leads to updating failure is still bothering me. I hope someone will help me to resolve these problems.