Html and css validation

• Remove margins and paddings from the block level elements before styling
• Don’t forget to comment your css
• IDs are unique, CLASSES can be repeated
• “divitus” ; Too many divs kill the div
• HTML and CSS validation
• Minimal css hacks ; keep it simple
• Back to tips corner

Make sure the HTML document you are working on is valid as per W3C recommendations.

It doesn’t need to be 100% valid but it will atleast tell you about unclosed and improperly nested tags/elements which could caude css problems.