`open` works just like checked for a checkbox input. You can set the initial state in HTML and CSS can respond to changes in the attribute if a user clicks it. Markup won't have programmatic control over the attribute by design, that's always done in JS by modifying the element instance.
`open` works just like checked for a checkbox input. You can set the initial state in HTML and CSS can respond to changes in the attribute if a user clicks it. Markup won't have programmatic control over the attribute by design, that's always done in JS by modifying the element instance.