Shortcodes: avoid hard coded styling

[deining]

Currently shortcodes contain hard coded styling, which is against good practice.
Affected shortcodes:

• card
• imgproc
• ...

These shortcodes need to be reworked so that styling is applied via scss.

Originally posted by @chalin in #1376 (comment)

I'd suggest adding custom styling through `cards-pace.scss`;
avoid the `border` class here, and even consider moving
the `me-4` into, say, `.td-card.card`.

[chalin]

Related (FYI):

• Cleanup: don't hard-code styles into layouts #783

[chalin]

(Might be an idea to fold this issue into #783)