For example borders: With a light background with a white box on it, it is important that these two elements are visually set off. The eye can then grab it easier better, otherwise both parts blur too much into each other. On a dark background, however, there should be no border. That doesn't look good at all and is not needed at all. When we then started to remove the borders, we noticed that we define them quite differently in LESS. As a result, they all look identical, but the notation was different, for example: