I'm mostly fine with markdown, but I just wanted to comment, this example in the post

    # Hi
    
    I am a <ins> simple </ins> _programmer_ doing
    <span class="fancy-text"> elegant </span> programming.
    
    <div class="animation">
    
    And here is my portfolio
    
    </div>

Might not do you think it does. markdown does not include html parser per-se. It allowes HTML but has rules like

    I am a <span style="color:green">super *grinch* yall</span>

will generate

    <p>I am a <span style="color:green">super <b>grinch</b> yall</span></p

It doesn't see the span element and turn off parsing.

Similarly, the div in the first example produces div, p, close-p, close-div, because the rule isn't "find he closing tag". The rule is something like "if the line starts with html then stop parsing and just copy until the next blank line.

All that said, I know the rules and generally know how to follow them. Of course I still run into the issue that even though there's commonmark, every site and tool is running their own variation which are incompatible.