[Plugin: Spoiler Block] Customizing style.css not working

Another bug just descovered,

After the upgrade, my customization dissapeared. It,s normal, as I only changed the css of the plugin, and it was rewriten.

Looking at the FAQ section of your plugin I read:

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How can I customize the spoilers blocks in my blog?

To customize the blocks of spoilers, just add the follow selectors in your css file: * .spoiler to spoilers closed blocks; * .spoiler-open to spoilers already clicked by users;
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So, I added the modified closed blocks to my style.css and it is ignored. It only works when I change it again into the css of the plugin.

https://www.ads-software.com/extend/plugins/spoiler-block/