Adjacent Sibling combinator
Since UXP v3.0
See: https://developer.mozilla.org/en-US/docs/Web/CSS/Adjacent_sibling_combinator
Example
Copied to your clipboard1sp-action-button + sp-action-button {2 margin-right: 0;3}
Since UXP v3.0
See: https://developer.mozilla.org/en-US/docs/Web/CSS/Adjacent_sibling_combinator
Example
Copied to your clipboard1sp-action-button + sp-action-button {2 margin-right: 0;3}