Validation is checking something against a rule. When you are beginners, this is very common that you will do many mistakes in writing your CSS rules. How you will make sure whatever you have written is 100% accurate and upto the W3 quality standards.
If you use CSS your code needs to be correct. Improper code may cause unexpected results in how your page looks or functions.
But if you want to validate your CSS style sheet embedded in an (X)HTML document, you should first check that the (X)HTML you use is valid.
Tool to check the validity of (X)HTML document: Validate (X)HTML document.
There are following good tools to check the validity of your CSS.
 |
W3C CSS Validator (World Wide Web Consortium) This validator checks your css by either file upload, direct input, or using URI - one page at a time. This validator helps you to locate all the errors in your CSS.
|
 |
The WDG CSS check validator lets you validate your css by direct input, file upload, and using URI. Errors will be listed by line and column numbers if you have any. errors usually come with links to explain the reason of error.
|
A CSS validator checks your Cascading Style Sheets to make sure that they comply with the CSS standards set by the W3 Consortium. There are a few validators which will also tell you which CSS features are supported by which browsers (since not all browsers are equal in their CSS implementation).
Why Validate Your HTML Code?
There are a number of reasons why you should validate your code. But major ones are:
- It Helps Cross-Browser, Cross-Platform and Future Compatibility.
- Increase Search Engine Visibility because you have good quality website.
- Professionalism: As a web developer your code should not raise errors while seen by the visitors.