"Delete Semester" (modal submit) button flicker-shows on staff semester page

[richardebeling]

@niklasmohrin we have an anti-flicker css rule in #1985:

EvaP/evap/static/scss/components/_confirmation-modal.scss

Lines 1 to 6 in e93b9f2

	confirmation-modal:not(:defined) > :not([slot="submit-group"]) {
	// Without this, the elements that are slotted into the dialog element show up as if they are just normal child
	// elements and disappear once the custom element registration is done. To avoid a short flicker of these elements,
	// we hide them until the constructor of the custom element has run.
	display: none;
	}

However, the selector here excludes the submit group. For me, on the staff semester index page, the red "Delete Semester" button thus shows for a short period during page load. Removing the > :not([slot="submit-group"]) part of the selector fixes the flickering for me, but I guess there was a reason for this exclusion?

[niklasmohrin]

First impressions: If I remember correctly, I intended to exclude the show-button slot, not the submit-group, not sure how it ended up like this. I can take a closer look later