In the case I'm trying to fix, Cataloging - Inventory, there are radio buttons for Home library or Current library, so the way radio buttons work those phrases should be the <label>s, so that clicking them toggles the buttons themselves. But the presentation of the whole page is geared to CSS for label, with only a little of it for .label, which assumes that whenever you have <fieldset class="rows"> ... <label> you will want that label to float: left and text-align: right, etc. Flatpickr is a somewhat similar problem: the project has decided that people who want to have the id in their dummy <input> which Flatpickr hides and replaces with its input transferred to the Flatpicker input are silly, because you can just wrap a label around the thing it is for, rather than having a sibling label with a for attribute pointing to the id of the input. But because of the floating and text-aligning, etc., of label, if you have <label>Set inventory date to: <input class="flatpickr"/></label> you get a ton of unwanted inherited presentation.
Phil I see you were CC'ed on Bug 39483... Did you have a chance to look at that code? It doesn't solve the problem of Flatpickr labels but my intention is to make form styling more flexible.
Yes, I read the docs from bug 39483 comment 0, and skimmed the code since I don't expect it to stick with me until I actually do it myself. And as an unrepentant writer of 1990s table layout, I love CSS grids in general and as a fix for this page specifically. Not sure when, if ever, I can get around to taking this bug though. After I filed this and fixed bug 37977 I asked my coworker who does inventory for us what her major pain points were, and only then found out that they were so severe that she invented her own inventory with item search and spreadsheets. My remit is to only do little 15 minute fixes of parts of Koha we don't use, so I'd have to fix this off the clock.