• I have searched the issues of this repository and believe that this is not a duplicate.

Expected Behavior

When using material-ui with Server Side Rendering -
There should be no validation issues shown by https://validator.w3.org

Current Behavior

There are many validation issues thrown by https://validator.w3.org when using Material-UI with server side rendering

Steps to Reproduce (for bugs)

1. Go to https://validator.w3.org
2. Enter https://material-ui.com/ in address Bar (since material-ui-next is exactly the use-case which is Server-Side-Rendering with Material-UI
3. There are many error generated, some of them quite easy to fix.
4. Enter URLs of other pages from components demo and there are some similar errors and some other errors as well

Context

I want to create an application which validates with W3C validator.

Your Environment