Your solution looks perfect and it's responsive. The issues report is clean too, congrats! Nice use of CSS variables, good to see that it's documented with comments.
My suggestions would be to take a look at one of the CSS methodologies, like BEM.
The HTML could be more semantic too, using
I noticed that there is a duplicate of
<link rel="preconnect" href="https://fonts.gstatic.com" /> in the HTML file that could be removed.