HTML and CSS Reference
If vertical_fountain.gif is a narrow, tall image whose color grows lighter
toward its base and whose length exceeds the length of the document
body, the resulting document might look like the one shown in Figure
Figure 5-22. A tall and skinny background
You can achieve a similar effect horizontally with an image that is much
wider than it is long (see Figure 5-23 ).
Figure 5-23. A long and skinny background