Unfortunately, there were no Universal Dashboard builds after the v3 beta2 and I wouldn’t be surprised if there were issues with it like you’re experiencing with the auto-refresh.
The reset every 60 seconds and is fixed in the most recent nightly build: Universal Nightly Releases
Here’s the most recent release notes for our upcoming 1.2.1 release: https://imsreleases.blob.core.windows.net/universal-nightly/46078/release.md
You’re right that there isn’t custom CSS yet. Are you hosting a custom CSS file? Just wondering how you are doing the custom CSS with v3. I wonder if wrapping the dashboard in UDStyle would allow you to use your custom CSS in the most recent version.