(@Ori Drori) I added following to app.css (the first CSS in index.html) to force it consider QuickGrids as low priority:

@layer QuickGrids, my-css;
@import '_content/Microsoft.AspNetCore.Components.QuickGrid/Microsoft.AspNetCore.Components.QuickGrid.bundle.scp.css' layer(QuickGrids);

But it doesn't help - the automatically created bundled css adds import without "layer(QuickGrids)" and I guess I cannot make it always add it?

I also tried adding a seperate file as the last css-reference with only that one, without success:

@import '_content/Microsoft.AspNetCore.Components.QuickGrid/Microsoft.AspNetCore.Components.QuickGrid.bundle.scp.css' layer(QuickGrids);

Anything I am missing? Can I force it to be layered with low prio although it's not me writing this file?

Ps. Sorry I cannot add a comment, just a new answer.