Not OP, but flexbox went very famously trough a few breaking changes throughout its early history: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Flexible

Not OP, but flexbox went very famously trough a few breaking changes throughout its early history: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Flexible_Box_Layout/Backwards_Compatibility_of_Flexbox https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_Flexibl... There were also some more subtle behavior changes a few years ago in the way webkit handled unprefixed flex-direction centering properties (align-items, justify-content) together with min-width/min-height attributes, switching from behaving closer to IE11 in this regard to basically emulating Blink. AFAIK neither behavior was really against-spec. And if you really want to go all-in with some really deep philosophical questions, I can suggest you the following: Is it possible to center text in a select box? https://stackoverflow.com/questions/10813528/is-it-possible-to-center-text-in-select-box https://stackoverflow.com/questions/10813528/is-it-possible-...