Photo credit: Danika Bannasch, UC Davis. Hereditary equine regional dermal asthenia (HERDA) is a genetic skin disease found in the Quarter Horse. The disease is characterized by hyperextensible, elastic skin, severe dermatologic lesions, and often scarring along the back and withers of affected horses.
Contents. 1  Introduction to style sheets. 2  Adding style to HTML Setting the default style sheet language. 3  External style sheets Preferred and alternate style sheets.  Cascading style sheets Media-dependent 1  cascades. Hiding style data from user agents.  Linking to style sheets with HTTP headers.
Hypertext Markup Language (HTML) The easiest and most popular web design language is Hypertext Markup Language, better known as HTML. This language is so simple you can type the syntax into a text editor, such as Notepad, save it with an .html extension and instantly have a web page.