Anti-Alias not working on smaller Scene

Is there a trick for getting anti-aliasing to work properly on smaller scenes - which are overlaid on top of big scenes?

Check out this fiddle here:

When you tap on any of the cubes you see in the main scene, a new smaller “detailsScene” opens up on top of the main scene - and the cube in that “detailsScene” is looking pretty bad. (It may not look all that bad there cause it’s such a small scene and such a simple object - a Cube, but trust me, in my real project I’m loading a “.glb” model and it looks terrible there. Totally fuzzy and out of focus. And I know it’s not the model that’s off, because when I load it into my main scene it looks 100% perfect. { Unless I have to re-load it for some reason into this smaller scene…?} )

Either way, in terms of the code, I’m pretty sure I set the renderer for this smaller scene in the proper manner, using:

detailsRenderer.setPixelRatio( window.devicePixelRatio );

(You’ll find that bit on line 192 in the JS of the fiddle code.)

Any thoughts on how this can be fixed?