I downloaded your codes, edited and tried them. I uploaded them to the server. The result is "Message sent successfully" but it doesn't display the input on the screen. It has connected to the database because it created the table in the database, but the rows are empty. Can you or anyone help me?
Such shortcuts are made possible by Emmet - code.visualstudio.com/docs/editor/emmet. Emmet should be enabled by default in VSCode without adding extensions. Are you using VSCode? Are other shortcuts working?
At 28:49, why can't you just use htmlspecialchars() instead of htmlentities()? If your webpage is using the UTF-8 encoding, we shouldn't have to worry about encoding every possible character that has an html character entity equivalent.
For future reference, it's recommended to use something like bin2hex(random_bytes(32)); for ensuring a truly non-predictable, entropic, and unique token.