Hey Ahmad,

The css is not encrypted, it's only minified to ensure that the css file is compressed and uses a much smaller file size so that your site loads up faster

I would not recommend you to modify the core css files in EasyDiscuss because if you update EasyDiscuss in the future, these changes would be overwritten. Instead, if you need to create custom css codes, you may do so by referring to our documentation here, https://stackideas.com/docs/easydiscuss/administrators/templating/template-overrides

If you still prefer to modify the minified file, you can always place the contents of the css file into https://unminify.com/ to un-minify them.