Modern Web Design with HTML5, CSS3, and JavaScript - Setting Cascading Style Sheets (CSS) Units and Highlighting Values

The video tutorial discusses different unit sizes used in web design, focusing on absolute and relative length units. It explains the use of pixels, percentages, and other units like centimeters and inches. The tutorial highlights the importance of relative units like em and rem for responsive design, and how percentages are used to adjust layout based on parent elements. Examples from the Mozilla Developer Network are used to illustrate these concepts.

What role does the viewport play in responsive design according to the text?

Describe how percentages are used in sizing and how they depend on parent elements.