@mui/styled-engine-sc

This package serves as a thin adapter layer to make styled-components work with MUI's styled() API. It does what it promises - if you need to use styled-components as your styling engine with MUI v5+, this package makes that possible. The TypeScript types are present and generally work, though you'll occasionally hit edge cases where the type inference doesn't match @emotion/styled behavior.

The day-to-day experience is fairly transparent once set up, which is both good and bad. Documentation is sparse - you're mostly left to figure out configuration by reading MUI's main docs and inferring how styled-components fits in. Error messages pass through from styled-components itself, which can be cryptic when theme integration fails. The getting-started experience requires understanding MUI's styling architecture deeply.

Migration between versions has been stable in my experience, but you're tied to both MUI and styled-components release cycles, which can create version constraint headaches. Most teams would be better served using the default Emotion engine unless they have a strong existing styled-components codebase.

This package is specifically designed to make MUI components work with styled-components instead of Emotion (MUI's default). The concept is straightforward—swap the styling engine—but the actual implementation requires understanding both MUI's theming system and styled-components' API quirks. Documentation is sparse and assumes you already know why you need this package, which made onboarding frustrating.

In practice, the styled() wrapper mostly works transparently, but debugging style issues becomes significantly harder. When things break, error messages don't clearly indicate whether the problem is with MUI, styled-components, or this adapter layer. I spent hours troubleshoming SSR hydration mismatches that turned out to be configuration issues specific to this package.

The GitHub issues are somewhat responsive, but the community is small—Stack Overflow questions about this specific package are rare. Most common use cases work fine once configured, but edge cases with custom themes or advanced component composition often require digging through source code. If you're already deep in a styled-components codebase, it's functional but expect some friction.

This package is essentially a thin wrapper that bridges MUI's styled() API to styled-components. In practice, it works as advertised but introduces additional supply chain risk by pulling in styled-components as a peer dependency. The abstraction layer is minimal—mostly re-exporting functionality—which means you're trusting both this package and styled-components' security posture.

From a security standpoint, there's nothing inherently dangerous here, but the package doesn't add protective layers either. CSS injection risks from user-controlled style props are passed through unchanged to styled-components. Error messages can leak component structure details in development mode, though this is typical for styling libraries. The package has no input validation or sanitization—it assumes you're passing trusted data.

The main concern is supply chain depth: you're adding an extra dependency that doesn't provide security value. MUI's default @mui/styled-engine (using Emotion) has similar risk profile but one fewer dependency. TLS/crypto isn't relevant here, but be aware that dynamic style generation from untrusted sources requires careful validation at your application layer.