This site has been made possible by the community of neocities and the fact that firefox allows you to "view page source". The general design was heavly inspired by mental-labour while the callous box in the ".diary" page comes from 401.
The beauty of HTML and CSS is that they have immediate practical applications. Here are some of the best resources I could find while learning.
MDN web doc - Up to date documentations about HTML, CSS and JS provied with interactive examples. The site design is amazing and the dark mode is rather soothing for late night coding.
W3Schools - Learning platform with guides and examples.