Most dads say they don't want anything. What they usually mean is: they don't want the effort of a gift to land wrong, or for you to feel obligated. They're not great at asking for what they actually want.
What most dads actually want is to know they did okay. That the things they showed up for — the practices, the drives, the quiet presence — were noticed.
What to put in it
Pick two or three things you genuinely appreciate about him. Not generic — specific. The way he handled a particular thing. A skill he passed on. Something he did when you were a kid that you only understand now that you're older.
Add a photo from something you did together. The fishing trip. The project. The game. Something that was just you two.
He might not say much, but he'll remember
Dads are often not the most expressive in the moment. He might say 'thanks, that's great' and move on. But he'll show his friends. He'll bring it up months later.
A personalized webpage is something he can open on his own when nobody's watching and read it again properly. That quiet re-read is where it actually lands.