Add a border around a form field.
If your field has a low contrast with the background colour, a stroke can help to create a contrasting border, which means you don't need to change either the foreground or background colour. A border also looks similar to what you'd find on a lot of paper forms, so it might help people realise that the element is a field.
If the border is too heavy, either in thickness or the colour is very dark, it might be visually distracting.
