A composite image showing how 3 browser natively handle error messaging when the @required attribute is used.

First is Firefox, which automatically outlines the form input – here a text input – with a red glow. It also produces a pop-up which reads “Please fill out this field”.

Next is Chrome, which automatically outlines the form input – here a text input – with a yellow/golden glow. It also produces a pop-up which reads “! Please fill out this field”.

Finally there is Opera, which does not provide a glow outline, but does produce a pop-up with a pale-red background and the error message “This is a required field”.