Guideline
There should be sufficient color contrast so that:
Links can be discerned from other surrounding text by either underlining or using a color contrast of at least 3:1.
Text can be discerned from the background by using a color contrast of at least 4.5:1.
You can check the contrast ratios for colors at http://webaim.org/resources/contrastchecker/.
WCAG References
For more information, Refer to the following topics
G183: Using a contrast ratio of 3:1 with surrounding text and providing additional visual cues on focus for links or controls where color alone is used to identify them (http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/G183)
G18: Ensuring that a contrast ratio of at least 4.5:1 exists between text (and images of text) and background behind the text (http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/G18.html)
ePortal Recommendations
In most cases, ClearPath ePortal automatically generates web applications that provide enough color contrast by default. However, possible exceptions occur when your data source project is MCP T27 or OS 2200 UTS. In this case, you can optionally retain the original colors from the terminal application; these colors may not meet the contrast requirements for accessibility.
Scaffolding MVC Applications to Ignore Terminal Colors
If you want to ignore the original colors used in the terminal application, do not select the option Preserve Screen Layouts and Styles when you scaffold the views for an MVC application. When you select this option, ePortal attempts to preserve the original terminal colors.
Refer to the following topics for more information:
Configuring Web Forms Applications to Ignore Terminal Colors
If you want to ignore the original colors used in the terminal application, set the MapTerminalHighlightCharactersToCSS presentation generation option to false.
Refer to the following topics for more information:
Styling Colors
Typically, you style your web application using the CSS color and background-color properties, or by using the web forms properties ForeColor and BackColor. If you change these proeprties from their default settings, use the tools at http://webaim.org/resources/contrastchecker/ to check contrast ratios.