A basic checklist for creating standards compliant websites.

• Markup should be semantic, well formed and generally valid.
• Aside from vendor prefixes and IE specific hacks, CSS should be valid
• Ensure a suitable contrast between background and foreground colours
• Content prints well or a print style sheet is provided
• All images have an alt attribute. Empty or otherwise
• Test your site with JavaScript disabled
• HTML reliant on JavaScript should be added as an enhancement. i.e added to the page using js.
• Don’t use inline styling
• Provide suitable fallback content for <object />,<embed />
• Provide skiplinks - link to content, link to top etc

• Avoid styling elements using IDs. use classes instead
• Class names should be descriptive of the content and not related to presentation
• Ensure CSS is structured in a modular way for easy reuse
• Avoiding adding unnecessary descendent selectors. e.g. .content .componentName .list li is less efficient than .componentName li
• Avoid attaching tags to CSS classes e.g ul.nav is less efficient than .nav
• Avoid adding more widths than necessary. Components shouldn’t need a width as they will get this from their column container.
• Use width: auto over width: 100% when resetting widths of block level elements.

• W3C CSS Validation Service
• CSS validator
• Accessibility - Cynthia Says Portal
• Accessibility - WAVE