Cascading Style Sheets: The Definitive Guide, Second Edition

Padding

Between the borders and the content area, we find the padding of the element box. It is no surprise that the simplest property used to affect this area is called padding.

padding

Values

[ <length> | <percentage> ]{1,4} | inherit

Initial value

not defined for shorthand elements

Applies to

all elements

Inherited

no

Percentages:

refer to the width of the containing block

Computed value

see individual properties (padding-top, etc.)

Note

padding can never be negative

As you can see, this property accepts any length value, or a percentage value. So if you want all h1 elements to have 10 pixels of padding on all sides, it’s this easy:

h1 {padding: 10px; background-color: silver;}

On the other hand, you might want h1 elements to have uneven padding and h2 elements to have regular padding:

h1 {padding: 10px 0.25em 3ex 3cm;} /* uneven padding */
h2 {padding: 0.5em 2em;} /* values replicate to the bottom and left sides */

It’s a little tough to see the padding if that’s all you add, though, so let’s include a background color, as shown in Figure 8-38:

h1 {padding: 10px 0.25em 3ex 3cm; background: gray;} 
h2 {padding: 0.5em 2em; background: silver;}

Figure 8-38. Uneven padding with background colors

As Figure 8-38 illustrates, the background of an element extends into the padding. As we discussed before, it also extends to the outer edge of the border, but the background has to go through the padding before ...