How can I implement form validation using CSS?

How can I implement form validation using CSS?

You can use CSS to style form elements based on their validation state. For example, you can use the :valid and :invalid pseudo-classes.

Can you give me an example of how to style a valid and invalid input?

Sure! You can use the following CSS:

input:valid {
    border: 2px solid green;
}

input:invalid {
    border: 2px solid red;
}

This will change the border color based on the input's validity.

What about custom messages for validation?

For custom messages, you can use the setCustomValidity method in JavaScript to set a message that will be displayed when the input is invalid.