Typographic hierarchy refers to the difference in type size and weight between text elements. It creates focus points that signal the user where to read; a successful hierarchy enables readers to easily scan content.
For information about how our typography relates to our visual identity, please visit the Typography page. For information about accessible text color combinations, please visit the Text Contrast page.
More Information in the WCAG 2.0 Guidelines
This color contrast tool is a useful resource for testing the compliance of any color combination.