The first and least complicated element of the the visual content is the Horizontal Rule, coded as <hr>. The line below is the result of the horizontal rule element.
In HTML5, the horizontal rule has been elevated from being a mearly decorative element, to being a structural element. The proper use of the horizontal rule is now to indicate a thematic break.
In the horizontal rule below, you can see that CSS properties can be applied to the <hr>, but not directly. In the example below, the hr has been given the id of #formattedhr. Then properties have been applied to the id and as such affected the hr. See the code snippet in the code box below the horizontal rule.
Style (Embedded in this page in <head> section: