Tagged “has”

By day I’m currently working on our Design System’s Table component. In order to achieve a design spec where the table has no bottom-border I needed to set:

1. all cells in the final row of the <tfoot> to have no bottom-border; but also
2. if there is no <tfoot> then set all cells in the final row of the <tbody> to have no bottom-border.

Modern CSS’s support for writing selectors which traverse the DOM up, down and sideways is pretty amazing here.

I’ve gone with:

tfoot > :last-child td, tbody:not(:has(+ tfoot)) > :last-child td { border-bottom-width: 0; }

(Some BEM stuff renamed for brevity but that’s the gist of it)

In the past we’ve had to bloat the backend layer with complex and awkward logic that adds “convenience classes” like .fe-Table-bodyLastRow but as Eric Meyer has been saying :has() in particular is going to remove the need for those convenience classes.

Hat-tip to Jhey Tompkins for his excellent recent article on :has which was a great help.

Great tip here from Jhey. He advises using a button with ARIA and a little JavaScript for your dark-mode toggle. And to apply the dark styles, use a CSS selector which targets the :root parent of the button when in “pressed” state and sets a root-level custom property to “on”.

:root:has([aria-pressed=true]) {
  --dark:1;
}

Seriously clever stuff!

And aside from the CSS, I really like the way Jhey advocates using a button rather than a form element such as a checkbox for this kind of interface, much like Léonie did recently.

The :has() CSS pseudo-class represents an element if any of the selectors passed as parameters match at least one element. But, it's more than a "parent" selector. That's a nice way to market it. The not so appealing way might be the "conditional environment" selector. But that doesn't have quite the same ring to it. How about the “family” selector?

The CSS :has() pseudo-class is a game-changer and can do more than act as a parent selector, as Jhey illustrates.