Heading 1: padding is added on the parent element (box)
2: padding adjusts the positional relationship of child elements in the parent element
3: padding will expand the box.
4: Want to keep the original size of the box: subtract the padding value from the width and height.
5: Add padding value to a single direction: padding-top/bottom/left/right:
6:
Padding setting method: 在这里插入代码片
padding:
10px around padding: 10px 20px top, bottom, left, right
padding: 10px 20px 30px top, left, right, bottom
padding: 10px 20px 30px 40px up right down left
7: Padding will not affect the background image
8: The value of padding cannot be negative! ! !