Color blocking isn’t for the faint of heart; it also isn’t necessarily for the short of stature.
This season’s big trend of color blocking takes bold opposites on the color wheel (as Ogi mentions, complementary colors), and puts them together for the widest contrast possible. The only other extreme color block combination is black/white.
So, primary colors on the color wheel are red, blue and yellow; secondary colors are purple (a mixture of blue/red), green (yellow/blue), and orange (red/yellow). The optimal color block scheme would be to take a red, mix it with a green, and add a third color (as in the first photo). You will also note the other photos pretty much follow suit.
For a petite person or one that is not necessarily slim, color blocking can cut you horizontally, making one look wider and larger than you’d probably like.