There are various problems here:
- you've added javascript into the css:global-css page in an html block below the css codeblock . It isn't ever going to get read there so delete it. Your CSS page must only contain CSS codeblocks, not html blocks or anything else;
- on the homepage of your site you've used a data form with a "header" field to add html hoping that it will go into the head section of the page. It won't. You can't add anything into the head section of a wikidot page.
- I don't know what a spoiler is but why do you need that button and the javascript to display the text anyway? If you want to alert users to add some text, in the live template in the presentation area above the ==== (above the field structure) just add:
"Insert what you want to say here"
without all that unnecessary javascript. You are making life more complicated than it needs to be. You have said that others might find it useful, but as you can do it more easily with Wikidot syntax and no javascript at all I'm not sure that's the case.
Wikidot code is very powerful; get to know it and it will do a huge amount of what you need without resorting to html and javascript.
Having said that, if you really want to add that "spoiler" button and text, and you are using data forms, then add it into a wiki field type as follows:
and then position it in the layout area of the page.
