This form was created with HTML, CSS GRID and ALPINE JS with a mobile first approach. It can be used as standalone Form or inside an iFrame.
For more information about Alpine JS check out the following link: https://alpinejs.dev/
I use the iframe-resizer from David J Bradshaw to enable the automatic resizing of the height and width of both same and cross domain iFrames to fit their contained content: https://github.com/davidjbradshaw/iframe-resizer