Jetpack: Block Editor Welcome Modal Has Incorrect Dimensions

[gwwar]

In Jetpack Master, it looks like the welcome modal isn't rendering as expected:

| Jetpack 8.6.1 | Jetpack Master |
| ------------- | ------------- |
| | |

| Jetpack 8.6.1 + Gutenberg Plugin | Jetpack Master + Gutenberg Plugin |
| ------------- | ------------- |
| | |

To Reproduce

• Install Jetpack Master or use the Bleeding Edge option in Jetpack Beta
  
• Enter the post editor at /wp-admin/post-new.php
• Click on Welcome Guide
  

Expected: Welcome modal appears with no scrollbars
Actual: Scrollbars are visible for both WP latest and Gutenberg plugin

[gwwar]

@retrofox @Automattic/ajax do you mind following up on this, looks like this broke from https://github.com/Automattic/jetpack/pull/15717/files#diff-79802d81ad46429980258e1ae67b1befR74-R79

We need a more specific selector, since this will be applied to any modals in the editor view.

[simison]

@retrofox FYI I noted in the PR as comments ~3~ 2 other CSS lines that needs fixing from that PR since they're leaking to core components.

[retrofox]

Thanks @gwwar and @simison for reporting the issue and help us how to fix it. It
s already tackled in https://github.com/Automattic/jetpack/pull/16144.
Just FYI, not sure if I introduced these changes but the whole team. It was the feature branch of the external media feature. 🙇‍♂️

[simison]

@retrofox no worries! Happens. Thanks for jumping so quick to fix it.