Hi @tuomasj! You’ve done a remarkably good job making an HTML form print-friendly, but for an invoicing product I think an MVP would need to include the capacity to generate a clean invoice with all formatting included. There are a lot of libraries build to output a PDF from arbitrary input, and I’d recommend investigating options for your platform. Not only will this improve formatting, but it will allow the user to email the invoice, print the invoice and keep a copy for their business. Even if you plan on adding user management in the future and save every invoice, people are almost always going to want to be able to export a clean copy.
Also, I personally would prefer to see labels on the two big text fields even if they are simply there to suggest what a user could enter. A huge part of online interaction is trying to make your users think as little as possible, and if I load that page and just see two empty text fields my brain has to go into analysis mode and check the rest of the form to find out that there are no other places to enter address and description. I also agree with @Charlie that there should probably be the option to upload a logo to personalize the invoice further than just the company name.
Excellent start though - keep it up!