What principle ensures that elements are visually separated from each other by a clear distance?

The principle that ensures that elements are visually separated from each other by a clear distance is contrast. Contrast is a fundamental design principle that involves creating differences between elements in a design. This can be achieved through varying colors, shapes, sizes, and spacing. By employing contrast effectively, designers can highlight distinctions, making it easier for viewers to differentiate between various components on a page. This separation helps in guiding the viewer's attention and enhances the overall readability and organization of the design.

Other principles like harmony, repetition, and alignment focus on creating relationships and consistency among elements rather than ensuring clear visual separation. For example, harmony creates a cohesive look, repetition reinforces visual themes, and alignment organizes elements along common edges or axes. These principles contribute to a unified design but do not necessarily address the need for differentiating elements with clear space between them.