Form in tooltip with text linked send button

While continuing to work on gergomatis.com I needed to find a simple contact form, something that fits the minimalist design of the site. I was spending a very long time with searching and I thought this was only possible with JavaScript [one of the simplest examples: Help Writing An Html Code (onclick Open Something)], but then I found exactly what I needed. No JavaScript, no complicated coding, a simple CSS rule is enough: