Discussion bring withStyles and makeStyles back https://github.com/mui-org/material-ui/issues/24109#issuecomment-780805118 When to us sx vs. flat props? https://github.com/mui-org/material-ui/issues/20012#issuecomment-782821025 Agree, sx whenever possible, flat props in my opinion are good for prototyping purposes... normalize supported colors use https://github.com/mui-org/material-ui/issues/24778 Agree, no objections, just we should be carefull on documenting the changes performance aren't great https://github.com/mui-org/material-ui/pull/24663#issuecomment-778492717 - is it still an issue? Last comment says it's fine, should we anyway investigate further? see where is the bottleneck and then consider performance flag Postponed scoped css with emotion https://github.com/mui-org/material-ui/issues/20461#issuecomment-809248743 POSTPONED after v5

Initial implementation example: const overridesResolver = (props, styles) => { const { styleProps } = props; return deepmerge(styles.root || {}, { ...styles[styleProps.variant], [`& .${buttonClasses.label}`]: styles.label, [`& .${buttonClasses.startIcon}`]: { ...styles.startIcon,

Positive feedback: Good looking docs Accessibility notes & When to use sections on each component's page Nice separation between unstyled (component page) and styled examples Support for React & Vue Negative feedback: Small set of components supported

Converting styles from JSS to emotion Things to consider when migrating component's styles to emotion. In v4 we were defining the styles like: export const styles = (theme) => ({ /* Styles applied to the root element. */ root: {}, /* Styles applied to the root element if `container={true}`. */ container: {