The HTML/CSS generated by AI doesn't work? Hallucinations and how to verify code

I asked the AI to 'write CSS to center text,' but nothing changed when I pasted it. The explanation sounds natural, but I can ...

Why does JavaScript sometimes work and sometimes not? Understanding the basics of loading order

I created a process to open a menu when a button is pressed, but nothing happens.Even with the same JavaScript, it suddenly started working when I changed where the file was loaded.In web development, ...