Apparence of invalid fields ?

[leplatrem]

In #496 I wanted to add this CSS rule:

input:invalid, input:focus:invalid {
  box-shadow: 0 0 5px 1px red;
}

And it made me realized that we had many places where forms are loaded with invalid values (usually empty strings :))

What should we do? Should we highlight them in red? Should we show them as red only when focused?

[glasserc]

Here's what I think would be "most optimal": invalid fields are highlit in red only if they are unfocused and only if they have been "touched" by the user, or the user has tried to "submit" the form (whatever that means for the form).

That seems hard, though. I'd settle for: invalid forms are shown as red once the form has been submitted once.