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Bartman, I really want to thank you for your help!

Please use the tags intended for multiline code. Apart from a more readable highlighting, it can be tested in the same browser tab without having to copy anything first.
Well, I used tags "LaTeX" and "/LaTeX" for latex-code. Do I need here some other tags? Well, let me try Code and \Code tags. The ...

Hello, friends! This little LaTeX-code works correctly and the reference to the Pythagorean theorem appears in the text as Reference to Pythagorean theorem: theorem 2.1 :

\documentclass[dvipsnames]{article}
\usepackage[many]{tcolorbox}
\usepackage{hyperref}

\newtcolorbox[auto counter, number ...