In the Document window, select
the horizontal rule.
Select Window > Properties to open the Property
inspector, and modify the properties as desired:
W and H
Specify the width and height of the rule in pixels or
as a percentage of the page size.
Align
Specifies the alignment of the rule (Default, Left, Center,
or Right). This setting applies only if the width of the rule is
less than the width of the browser window.
Shading
Specifies whether the rule is drawn with shading. Deselect
this option to draw the rule in a solid color.