By A Mystery Man Writer
How to make a DIV content responsive - Quora
What am I doing wrong? margin padding - Language Help - Codecademy Forums
Codeacademy
What is the use of box-sizing property in CSS ? - GeeksforGeeks
Introduction to HTML-CSS-Javascript.pdf
The CSS Box model: each element as a box, by Akshat
CSS Flashcards
SIZING ELEMENTS - Percentages: Padding & Margin - CSS - Codecademy Forums
Slides - Merlin - Software Witch