Tours gets clipped/misaligned when scrolled away from initial position

[microbit-grace]

Repro

1. Open CreateAI project with lots of data samples or in a narrower window (enough to have a horizontal scrollbar).
2. Connect to micro:bit.
3. Show tour and see certain parts get clipped out.

In more extreme cases, we might not even see any of the tour and won't be able to exit it if the highlighted bit is very much off screen.

Misalignment happens for testing model page