I'd like to create a registration form something similar to this:
Does anybody know which language mediafire created their registration form with please?
The look is created by HTML and CSS, of course, and the on-page validation behavior by JS. The processing is presumably done with PHP, given that the page has a .php extension.
Thank you! Is the CSS what is changing the colour of the box from white to red when you click in a field and click out?
The color and the little icons are done with CSS. BUT ... the new CSS rules apply to the boxes with the help of JS. If the box isn't filled out properly, JS adds a class of "error" to the input, and then the CSS styles associated with that class apply to the input.