Material-ui: [TextField] CSS API missing

[Primajin]

• [x] This is not a v0.x issue.
• [x] I have searched the issues of this repository and believe that this is not a duplicate.

Expected Behavior 🤔

Show CSS API like https://material-ui.com/api/input-label/#css

Current Behavior 😯

CSS API missing

Steps to Reproduce 🕹

https://material-ui.com/api/text-field/#css

Context 🔦

I wanted to look up how to pass down a class to the helper Text

Your Environment 🌎

Online Documentation

| Tech | Version |
|--------------|---------|
| Material-UI | v4.2.0 |

[oliviertassinari]

This component doesn't inject any styles. The simplest strategy is to open the dev tools, and to pick the global class name.

[Primajin]

OK then, but shouldn't we at least say that in the docs then? I was passing stuff to classes and got the error "Only root is available" - so should we then at least list that under CSS API?

---

On the other hand it would be great if you _could_ pass down classes.
My workaround is now passing a class down to classes={{ root: classes.helperText }} and then having

helperText: {
  '& p': {
    //my overwrites here
  }
},

[oliviertassinari]

Oh, I was wrong. Thanks for raising that the root key was working. I had forgotten that we introduced it for global theme overrides.
https://github.com/mui-org/material-ui/blob/22ba481fd549ffd35199846d2c313881406256a4/packages/material-ui/src/TextField/TextField.js#L21

Ok, in this case, I think that we should export the style const so the API generator can pick it up:

-const styles = {
+export const styles = { 

[m2mathew]

I got this one 👍