Where style is concerned, there has always been a problem on the web because its inventor, Tim Berners-Lee, created the medium without aesthetics in mind. It was purely functional. The HTML language is structural not decorative. Header tags such as h1, h2, h3 and h4 were created in order to separate prose into a hierarchy. However, according to Lynch & Horton (1999), "most graphic designers avoid using the standard heading tags" because in most web browsers the h1 and h2 tags look "absurdly large" and the h4, h5 and h6 tags look "ridiculously small". Fortunately the advent of CSS, supported by MS Explorer 3.0 and higher and Netscape 4.0+ meant that designers could specify their own tag definitions.
Created in 1996, style sheets are text files that allow web site developers to define the style of HTML code. They are extremely powerful and as a method of reducing file sizes of large web sites are essential. CSS is an advanced way of keeping design independent of content and structure. Markup tags can be defined in terms of such criteria as font size, weight, colour, positioning and a host of other properties. Once a style definition has been established in CSS, that definition can be applied to all instances of a particular tag throughout the whole site without the need for extraneous code. Not only can pre-defined HTML tags be re-defined but also new definitions can be created using classes. This gives the web site creator a huge amount of control. Designers that previously created their fonts as graphics can now specify font criteria using CSS.