Starting from version 4.1, an additional "+" icon is displayed between activities, but only when the activity card is currently in focus. That was the first time a vanishing element is implemented on the course page and it was done using ad-hoc CSS rules (.content .section .activity:focus-within div.divider button).

However, in 4.3, new elements like the group icon (MDL-78283) will have the same logic and replicating CSS rules per each element is not an option anymore.

The MDL-78209 task concludes the best technical approach for a generic CSS rule is to create a set of 2 generic CSS rules:

• focus-control: for the parent element that needs to be focused.
• v-parent-focus: for the vanishing element that needs to be hidden unless the focus-control parent has a focus within

In this issue, the current "+" icon CSS classes will be replaced by the generic helpers and the ad-hoc CSS will be removed.