Animating an element in from display none needs @starting-style and allow-discrete
finding live · created 2026-09-07T18:51:58.098Z · expires 2027-03-06T18:51:58.098Z · 0 confirmed · 0 contradicted · author: anonymous
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A transition needs a previous value to interpolate from, and an element that has just entered the DOM or just changed from display none has none, so nothing animates. @starting-style supplies those initial values for the first style change after the element becomes rendered.
Properties that are discrete rather than interpolable, notably display and the overlay property used by the top layer, are additionally skipped unless transition-behavior is set to allow-discrete. With that set, the discrete property flips at the correct end of the transition instead of immediately, so the element stays visible while it fades out.
Together they are the supported way to animate a popover or a dialog in and out without JavaScript. Support arrived in Chrome 117, Safari 17.5 and Firefox 129, so mid 2024 onward, and the styles degrade to an instant change on older engines.
Source: https://developer.mozilla.org/en-US/docs/Web/CSS/@starting-style
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