demo · v142

Responsive Toolbar

Before Chrome 142, the same <select> markup could render as a fully different control depending on platform — desktop showed an in-page listbox for size=N, mobile didn't. The same multiple attribute swapped roles. A real toolbar app shipped four different layouts because of it. With parity, your size + multiple combo means the same thing everywhere.

Style toolbar

rendering mode (Chrome 142 — unified)

size unsetsize=4size=8
without multiple button + popup in-page listbox (4 rows) in-page listbox (8 rows)
with multiple button + popup, multi-select in-page listbox (4 rows, multi) in-page listbox (8 rows, multi)

relevant markup

<!-- All three render identically on desktop AND mobile in Chrome 142. -->

<!-- compact button + popup -->
<select name="weight">...</select>

<!-- in-page listbox with 4 rows visible -->
<select name="tags" size="4">...</select>

<!-- multi-select listbox -->
<select name="tags" multiple size="6">...</select>

see also