Most guides about Google Forms and your website answer a question you did not ask.
Search for how to replace a Google Form with your own HTML and you get three kinds of answer. Embed the iframe but style the container. Use a service that hides Google's branding. Or the clever one: build your own HTML form and point it at Google's endpoint, so responses still land in your existing spreadsheet.
All three keep Google Forms in the loop. If that is what you want, they work, and I will show you the third one because it is genuinely useful when you need it.
But if you actually want the Google Form gone, replaced by markup you own, here is how that works and what it costs you.
One-line summary: Google Forms does one thing your static site can't, accept a POST; swap that for a form endpoint and you get your markup back, at the cost of owning spam and losing free-unlimited.
