Brecht De Ruyte explores new CSS gap decorations that let you style spacing in grid and flex layouts without workarounds. The column-rule and row-rule properties draw lines in gaps, while rule-break, rule-inset, rule-overlap, and rule-visibility-items fine-tune intersections, extension, and conditional display. The rules are animatable too.
utilitybend.com/blog/css-is-filling-the-gaps-with-rules-a-way-to-style-gaps-in-grid-and-flex