The most fundamental change in v6 is the migration from Less to SCSS with CSS variables as the primary theming interface. Updating theme values is now as simple as overriding variables at runtime - no rebuilds or tooling tweaks required. Consult the CSS Variables guide for the full variable list, and try the Palette tool to fine-tune brand colors visually. Additional Style Improvements Logical properties: margin-inline-start etc. replace physical properties for native RTL support.
Sometimes I want to set the value of a CSS property to that of a different property, even if I don't know what that value is, and even if it changes later. Unfortunately though, that's not possible (at least, there isn't a CSS function that specifically does that). In my opinion, it'd be super useful to have something like this (for interpolation, maybe you'd throw in there as well): /* Totally hypothetical */ button { border-radius: compute(height, self); border-radius: compute(height, inherit); border-radius: compute(height, #this); }