[capitainenemo]

I assume "FE" means "form error" - personally I agree with you, but you can still make it work without it.. "progressive enhancement" where validation is still done serverside which is an absolute must even if you do use JS for that.

Also, HTML5 validation is pretty darn powerful these days. Check it out if you haven't already.

[easrng]

Probably "front end". But yeah, you can do a lot with just html and css.