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HTML Guide

Free site validation

Find out what web pages on your sites are affected by HTML issues.

Only “0” can be a “unit”. You must put a unit after your number

When specifying a numeric value for a CSS property, remember to always include the units, like 3px or 3em. Only the 0 value can go without units, and instead of 0px you can just use 0.

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Related W3C validator issues