Technique C25:Specifying borders and layout in CSS to delineate areas of a Web page while not specifying text and text-background colors

Description

The intent of this technique is to specify borders and layout using CSS and leave text and background colors to render according to the user's browser and/or operating system settings. This allows users to view the text in the colors they require while maintaining other aspects of the layout and page design such as columns of text, borders around sections or vertical lines between a menu and main content area. It will also prevent some display issues in some browsers when pages contain Javascript pop-up boxes or drop-down menus and have the colors overridden.

Borders and layout indicators help many people with cognitive disabilities, as does flexibility over the text and background colors. Sometimes these two needs are in conflict when the user has to over-ride the author's color selection of text and background in the browser and the browser also removes the borders and the intended layout. This can mean the page is displayed in a single column with one block of content below the other, which can result in unnecessary whitespace and long lines of text. It can also mean that pop-up boxes gain a transparent background, superimposing the text of the box on the text of the page, and drop-down menus either become transparent or gain a dark-grey background. When a Web author does not specify the colors of any text and background, while specifying border colors and layout, it is possible, in most popular browsers, to change the text and background colors without affecting the other (author-specified) CSS declarations.

Examples

Related Techniques

• G17: Ensuring that a contrast ratio of at least 7:1 exists between text (and images of text) and background behind the text
• G18: Ensuring that a contrast ratio of at least 4.5:1 exists between text (and images of text) and background behind the text
• G145: Ensuring that a contrast ratio of at least 3:1 exists between text (and images of text) and background behind the text
• G148: Not specifying background color, not specifying text color, and not using technology features that change those defaults
• G156: Using a technology that has commonly-available user agents that can change the foreground and background of blocks of text
• C23: Specifying text and background colors of secondary content such as banners, features and navigation in CSS while not specifying text and background colors of the main content

Tests