What Is Style?
Style is the science of identifying, relating to, and choosing the most appropriate style for a specific object or situation. It is the skeleton of a design discipline. Style has a number of different categories, including formal, semi-formal, and casual design. A type of style that is often used is called a style guide or a typological design guide. The most common formal styles are the classical style, which govern the usage of white space and the main components of design, and the structural design, which are based on a clear hierarchy of components.
In practical terms, style primarily refers to the appearance or style of an item, or technique of doing a certain activity. For instance, in web design, a designer using CSS can quickly switch the appearance of several headings on a single page at once by adjusting the style of each heading. However, the primary difference between the two is that in CSS, the visual formatting of one element is pre-determined before any of its children is rendered. This means that, unlike HTML, the style is more flexible and less dependent on the layout of the actual document. This is why there are usually two types of CSS, one that is used specifically for styling items in a document and one for referencing the style definition of an element.
The major purpose of CSS is to provide tools for designers to rapidly change style according to the current state of the document. With CSS, one can quickly change the appearance of objects (like buttons) without disturbing their layout. This is in contrast to HTML, where changing the style of an element changes its position in the document, sometimes causing unwanted lines of text to be lost.