my solution Base-Apparel

Good evening, I made this page in 1440 x 768, I had some problems that I would like help with, I couldn't put the "input email" to see if the email was valid by js just to see if it was empty or not I tried use the css pseudo class ":invalid" but it didn't work I researched but I couldn't find any simple way to validate an email so I would like help if anyone knows a simple way, I would also like to know of some way to put an image in the "input: submit". I'm still learning js so I would like some tips, thank you everyone.