This chapter is from the book
This chapter is from the book
This chapter is from the book
Using Style IDs
When you create custom style classes, you can use those classes as many times as you would like—they are not unique. However, there will be some instances when you want to have precise control over unique elements for layout or formatting purposes (or both). In such instances, look to IDs instead of classes.
A style ID is a custom set of formatting specifications that can be applied only to one element in a web page. You can use IDs across a set of pages but only once per time within each page.
For example, suppose you have a title within the body of all your pages. Each page has only one title, but all the pages themselves include one instance of that title. Following is an example of a selector with an ID indicated, plus a property and a value:
p#title {font: 24pt Verdana, Geneva, Arial, sans-serif}
Notice that this selector includes a hash mark, or pound sign (#), after p, followed by a descriptive ID name. When referencing a style ID in HTML code, simply specify the ID name in the id attribute of an element, like so:
<p id="title">Some Title Goes Here</p>
Everything between the opening and closing <p> tags will appear in 24-point Verdana text—but only once on any given page. You will often see style IDs used to define specific parts of a page for layout purposes, such as a header area, footer area, main body area, and so on. These types of areas in a page will appear only once per page, so using an ID rather than a class is the appropriate choice.