Begin with semantic HTML. Native buttons, links, labels, headings, and landmarks provide behavior that custom elements must otherwise recreate. This foundation helps assistive technology and makes interfaces more resilient.
What matters in practice
Keyboard navigation should follow the visual and logical flow. Focus must be visible, dialogs must manage focus deliberately, and every action must remain available without a pointer. Contrast and zoom behavior should be tested early.
A useful rule
Automated checks catch only part of the problem. Combine them with keyboard testing, screen-reader checks, and feedback from people with different access needs. Accessibility is a quality attribute of the whole system.