Fix #3528 - Fix CSS for description textarea

[emilio]

Make the progress bar not overlap the textarea. While at it, also remove useless content: "" rules which do nothing, and an useless width declaration which also does nothing because it's the same width as the block would have minus margins.

This PR fixes issue #3528

Proposed PR background

See #3528

[emilio]

cc @karlcow

[karlcow]

This change the initial design (not that I'm fond of it).

#3534 design

#3535 design

Though yes the full thing could be redone a bit better.

[karlcow]

ok indeed in my design long lines are not working.

[karlcow]

This will fix it. Let's merge it and we might need to open an issue to solve this design later on.
At least it's usable now.

Thanks @emilio

[karlcow]

Thanks for the contribution.

[emilio]

ah, didn't notice the focus state was in the textarea.

Should be fixable by moving the outline to .progress-textarea with something like .progress-textarea:focus-within

[karlcow]

ok deployed :) v39.0.1...v40.0.0