Ink Bar
The bar travels and resizes to the label it lands on.
Usage
OverviewActivityFiles
Meant for
Examples
On a Tabs
Width and position animate together, which is what makes the underline feel attached to the word rather than sliding past it. The Tabs' own line indicator is hidden and the bar takes its place; --wm-x1…3 and --wm-w1…3 are the measured trigger positions and widths.
The class is wm wm-ink-bar — the first half is the marker the trigger and reduced-motion rules hook into, the second is the effect.