
The header class .MuiAppBar-colorPrimary should override .MuiPaper-root and hence show blue color instead of white.

MuiPaper-root is overiding .MuiAppBar-colorPrimary.
I would try to reproduce it and edit this. I thought someone might have idea whats going on.
I have single app root, no jss code etc. The only extra dependency apart from default react-material stack is unstated. I see double .MuiPaper-root class, may be something is off there.
Also I haven't used even themeprovider tag or baseline anywhere
| Tech | Version |
|--------------|---------|
| Material-UI | v4.0.1 |
| React |^16.8.6 |
| Browser |Chrome|
|material-table| 1.38.0|
This issue might be related with https://github.com/mui-org/material-ui/issues/16100
Can you please screenshot how styles look like within your <head>? No matter what classes are used by the html elements, when at the same level of specificity, it all depends on the which rules are rendered the first and the latter ones will always override the former ones.
Thanks to #15610 I found the problem
The problem seems to lie here.
import Paper from '@material-ui/core/Paper/Paper';
changing to this removed the issue.
import Paper from '@material-ui/core/Paper';
feel free to close :)
@dereksangshi if you still want the screenshot:

Thanks for this issue, for us the problem was importing Paper like this
import Paper from '@material-ui/core/Paper/index';
It took me several hours of debugging because the import was done in another component
Most helpful comment
Thanks to #15610 I found the problem
The problem seems to lie here.
import Paper from '@material-ui/core/Paper/Paper';changing to this removed the issue.
import Paper from '@material-ui/core/Paper';feel free to close :)