Your grandma has probably given you a thousand small things over the years — the food, the visits, the advice you only understood later. Making her something personal is a way to say that it all registered.
A webpage works well here because it doesn't require her to do anything complicated. She gets a link, opens it on her phone, and sees something clearly made for her.
What to include
A specific memory of time you spent with her — her house, her kitchen, a trip, a holiday. Something that captures what those visits actually felt like.
Something you've carried from her — a skill, a saying, a way of doing something. Grandparents often don't know how much of them travels forward into their grandchildren's lives.
A few photos. The older ones she might not have seen recently. Her at a younger age. Family gatherings. Ordinary days that were actually extraordinary.
What will happen
She'll show it to your grandpa. She'll call your mom. She'll forward it to aunts and uncles. She'll bring it up the next time you talk.
It's the kind of thing grandmas keep. Not in a drawer, but on the phone — the one thing on the screen she knows how to find.