Incorrect description of tts:position example.

[palemieux]

The bottom of the region seems to be positioned 10% * (root container region height) from the bottom of the root container region.

This is inconsistent with the clause percentage value component for a vertical position offset is relative to the height of the positioning rectangle minus the height of the associated region.

[palemieux]

See test and renders at w3c/imsc-tests#49

[skynavga]

The CSS spec I derived from (https://www.w3.org/TR/css-backgrounds-3/#the-background-position) is rather vague. I will check further with CSS implementations.

[skynavga]

OK, I verified that both offset and edge position calculations are the same. See https://codepen.io/skynavga/pen/BxVrRj. I will update the description of the example. I think we don't need to actually change the image since one can't really (visually) discern what offset appears in the image, and the image is intended to only be representative.

[palemieux]

Here's a render in case it helps.

Also, the region style should have something like <style tts:fontSize="40%"/> otherwise the text is too big.