What are the Chrome developer-tools highlight colors?

In past versions of Chrome, the developer tools allowed you to inspect page elements and would highlight them in blue. Recent versions of Chrome highlight elements in blue, but also have green and orange areas as well.

What do the colors mean?

Solution 1:

The colors represent the areas of elements corresponding to the CSS box-model.

• Blue is the content
• Green is the padding
• Orange is the border
• Red is the margin

(The choice of similar shades of orange and red are probably not the best.)

You can see this in the Metrics section of the developer tools (which is hidden by default):

Solution 2:

Update 2021

Also purple dashed area is displayed now. It represents the available space to expand:

see here