Indigo Design System v1.2.0


Indigo complies with the World Wide Web Consortium’s (W3C) web content accessibility guidelines (WCAG 2.0), ensuring that people with diverse abilities can easily use any USAC digital product or web property that adopts its framework.

Color Contrast

Indigo color pairings meet WCAG Level AA contrast ratio, which is 4.5:1 for normal text and 3:1 for bold or larger text. This compensates for the loss in contrast sensitivity often experienced by users with vision loss equivalent to 20/40 vision.

All Indigo components have already accounted for these contrast measures; however, a color contrast reference is available on the Indigo Color page to assess instances when applying unique color combinations within a USAC digital product or web property.

Standard Markup

Indigo components incorporate standard markup and ARIA roles based on W3C standards and industry best practices. ARIA (Accessible Rich Internet Applications) is a spec from the W3C created to improve accessibility of applications by providing extra information to screen readers via HTML attributes. Following these standards allows assistive technologies to gather information, activate and keep current on the status of user interface controls.

Applicable component guideline pages have sections describing any special accessibility considerations that should be taken when implementing the specific component in products / web properties.

Keyboard Alternatives

Indigo provides keyboard alternatives for mouse-based actions by using HTML form controls and links. This ensures full control of components for those with low vision or who use alternate keyboards or input devices.

Text Alternatives

Indigo components provide structured ways for USAC digital products or web properties to incorporate alternative text (via `alt` tag) during implementation. Alternative text are a primary method used to make information accessible, because they can be rendered through various modalities (i.e., visual, auditory or tactile) to meet specific needs.


Need more Help?

If you are looking for more guidance or specification around Indigo accessibility, send an email to