The contrast and uniformity are the two concepts used in visual design to direct the attention of people in a web interface.
The contrast creates the relationship between the elements, it creates meaning and above all creates hierarchies of content and information.
Having a design without contrast means flatten the vision: the vision does not stop at anything and nothing seems important.
While a design where everything is different and nothing repeats itself loses meaning.
If everything is important nothing is important.
If everything is different it is nothing special.
The key thing is to define a single and clear starting point in the page, which is a point where the reader immediately starts scanning the page and defines the beginning
of the navigation path for the important information.