It’s important for to create a balanced layout. In web design we refer to heavy (large and dark colors) and light (small and lighter colors) elements. Using the correct proportion of each is critical to achieving a balanced website design.
In color theory, contrasting colors are ones placed opposite one another on the color wheel (see also complementary colors). Web design offers a few other areas where contrast is applicable. Designers look at contrasting sizes, textures and shapes to define and draw attention to certain sections of the website.
We touched on this a bit when discussing contrast. Emphasis is a design principles founded in the intentional “highlighting” of certain important elements of the website layout. It’s important to note that if you emphasize everything on the page you end up emphasizing nothing. Imagine a page in a book where 80% of the content is highlighted in yellow…does anything really stand out? This is the time to take a look at that Information Architecture for direction.
Also called repetition or rhythm, consistency is a critical web design principle. For example, clean and consistent navigation provides the best user experience for your website visitors.
Unity is the relationship between the various parts of the website layout and the composition as a whole. Based in the Gestalt theory, unity deals with how the human brain visually organizes information by grouping elements into categories.