Board thumbnail is not showing whole board when board has absolute or fixed position

[olehrakwix]

Steps:

• start new project from E-Commerce Starter template with Codux
• install dependencies
• observe Intro and 5 - Cart boards on home screen:

• open these boards, observe how they should look

Technical details
This issue is caused by change in this PR: #1131
The thing is that previously we were applying board environmentProps settings to a board container (board-canvas), and width and height were set explicitly
Now, board container (board-canvas) has no width and height set. Because mentioned boards root element has position: absolute, this root element is not affecting its parent html element (board-canvas). Thus, board container has size of 0x0:

Because of that, Codux logic to measure board size and fit it into thumbnail is failing.
I think, we should explicitly set width and height for board-canvas element