HTML and CSS Reference
may thicken the rules with the size attribute. The required value is the
thickness, in pixels. You can see the effects of this attribute in Figure
5-2 , as constructed from the following source:
[*] A pixel is one of the many tiny dots that make up the display on your computer. While display sizes
vary, a good rule of thumb is that one pixel equals one point on a 75-dot-per-inch display monitor. A
point is a unit of measure used in printing and is roughly equal to 1/72 of an inch (there are 72.27 points
in an inch, to be exact). Typical typefaces used by various browsers are usually 12 points tall, yielding
up to six lines of text per inch.
Figure 5-2. The popular browsers let you vary the
horizontal rule size
This is conventional document text,
followed by the standard 2-pixel tall rule line.
The next three rule lines are 12, 36, and 72 pixels