.ui.cardsIt respects the top and bottom margins.
It sticks too close to what comes before and after. It's especially bad for mobile.
2.3.1
This is intended if you want spacing between your elements that is up to you or you could use a hidden divider https://semantic-ui.com/elements/divider.html#hidden
It's not about adding spacing. The .ui.cards eats up margins because it uses negative margins. This is about being a good citizen.
How to be a good UI component: Don't take what's not yours, unless you know it's safe to do so, e.g. a component that's meant to be used together.
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How to be a good UI component: Don't take what's not yours, unless you know it's safe to do so, e.g. a component that's meant to be used together.