If you have an idea for a product, do not start with a design doc. Build a quick visual prototype and share it with the team and stakeholders instead.
I have been doing this a lot, and it is working out really, really well. A doc full of text requirements makes people imagine your vision inside their own head, and every person imagines something slightly different.
A prototype removes this delta entirely. People see the actual thing, and suddenly they are reacting to it instead of guessing at it.
By the way, this prototype is throwaway work with just frontend and mock data. No backend, APIs, or database.
Just dump your requirements into your favourite coding agent and let it spit out a prototype. Iterate on it, host it on Vercel or something, and share it with the team.
The feedback you get back is also just better. Practical, pragmatic. Everyone is literally on the same page.
Once you get the feedback, iterate on the prototype directly. Ship the change, repeat. The prototype becomes the living spec, and it stays far more convincing than any text ever could.