Using clip-path to define custom shapes inside a container!
Percentages units has the benefit of keeping things responsive
There is many clip-path functions: inset, circle, ellipse, polygon and... path for maximum flexibility

clip-path: inset(x x x x) is useful for clipping blocks of an element and using it as a "controlled" overflow.
This clip-path value represents a thunderbolt: polygon(100% 0, 20% 50%, 35% 50%, 0% 100%, 70% 50%, 50% 50%)

We can transition or animate clip-path. There's one condition. The path must have a consistent structure. For example, if we transition a polygon, that polygon must have a consistent number of points.

Skewing effect: https://codepen.io/enbee81/pen/yLyrmyg

and cyberpunk buttons in CSS: https://jhey.dev/writing/css-cyberpunk-2077-buttons-taking-your-css-to-night-city/