In dark mode of IFDB, the text input fields can sometimes be a little difficult to see until you click inside the field (when you do that, the border brightens up). See, for example, the “Search tags” field at the bottom of this screenshot. The border is gray and very narrow. (The “search for games” field above that is a little easier to see, but still subtle.)
Ok, originally, the “Search for games” area had a 2px border. (You couldn’t see it in dark mode, though, because it was black.). And originally the “search for tags (etc.)” search bar had a 1 pixel border.
The colors in all the screenshots below are the same.
Here’s both search bars with the original border thicknesses (2px above, and 1px below):