One way to implement and assure accessibility throughout your website development and updating cycles is to create an accessibility style guide. A style guide is a design document that establishes a set of standards, in this case, accessibility standards.
An accessibility style guide gives explicit and consistent guidelines for developers to help them build accessible sites. Accessibility standards also enhance SEO and UX by putting into place best practices of anticipating, planning for, and solving user impediments.
Accessibility style guides should address common issues first, such as color contrast and form elements. Be sure to include all of the issues your accessibility and usability experts have noted—don’t assume that others will have this knowledge. And, try to align any existing design style guide with your accessibility style guide to ensure that you are creating consistent and compliant websites.