Blogger post url prefix

It looks like this when I use data:post.url in Blogger; the shape I want to show; /2021/04/post-name.html How can I achieve this?

How to add two or more spoiler button in my blog

Question: I have a spoiler code that works well in my Blogspot blog. But when I place the same code two times in my blog (like spoiler 1, and spoiler 2), spoiler 1 works well, but spoiler 2 does not open. Why? How do I fix it? Please help. I do not know programming. Here is code of spoiler that I am using: Answer Works for me when I rename the ID