To style all <input> elements with an invalid value, use the CSS :invalid selector.
Example
You can try to run the following code to implement the :invalid selector −
<!DOCTYPE html> <html> <head> <style> input:invalid { background: red; } </style> </head> <body> <h2>Heading</h2> <input type = "email" value = "InvalidEmail"> <p>The style (red color background) appears if you type an irrelevant/ invalid email address.</p> </body> </html>