Thank you for help! In fact, I am using responsive bootstrap in my web application already. I more need a tool that can generate me a nice layout. Something that is different than the default templates. I could hire a GFX artist, but I prefer something automated because it will be temporary, for a demo and need it quick.
I don't think there's a demand for log-in pages, so I don't think there would be such a thing other than templates.
You can use a bootstrap template and use a different bootstrap theme..
Or you could always do it yourself. If you are working on a blockchain app, you must probably know how to make a simple log in page