Change Text Box Color using Required Field Validator. No Extender Controls Please

Question

I need to change color of TextBox whenever its required field validator is fired on Clicking the Submit button

Answer 1

Very late to the party, but just in case someone else stumbles across this and wants a complete answer which works with Bootstrap, I've taken all the examples above, and made a version which will work with multiple validators attached to a single control, and will work with validation groups: