“Rejoice, fellow Sketch Users! Sketch 3.9 finally delivered us the ability to create truly fluid layouts. Generally speaking, fluid layouts (a sort-of subset of responsive layouts) are those whose elements can resize, float, or hold their position as the size of their container changes.

In Sketch you know these containers as Groups, and so Sketch calls the feature Group Resizing, offering similar functionality to the Fluid Plugin for Sketch; the difference is that the functionality is now native to the app and therefore offers a better user experience…” – Daniel Schwarz for SitePoint