Styles are possible with native text view, otherwise we couldn’t have fonts and colors and contenteditable and selection within <p>. I think you mistake “input core” with “web input element” here. The core I’m talking about is a text cell with characters on it that has no concept of own border. Controls like NSTextField, Win32.TextBox, GtkEntry - they all have platform text input (and output) system underneath. In case of gtk it implements it itself, cause X has none. The thing that implements all the familiar behaviors of the text input that you know.

So yes, compared to HTMLInputElement these are absolutely custom. But for a platform, absolutely native.