How to highlight code with “Code Syntax Block” snippets?

Short version Have installed https://wordpress.org/plugins/code-syntax-block/ . Add code block. Add language-[language] class to <pre> tag in “Edit as HTML” mode, for example language-css. Long version I am using https://wordpress.org/plugins/code-syntax-block/ plugin but I did not notice in their documentation how to use it. I had to find a way myself. But problem is at the same …