v2 docs search modal cut off on smaller screens

Description

When viewing the v2 docs site at https://next.gatsbyjs.org/docs, while using the the search field, the pop-up window appears to be cutoff on smaller screens (A 13" Macbook Pro for example), or in smaller browser windows, when there is a large amount of search result content.

Steps to reproduce

• Visit https://next.gatsbyjs.org/docs on a device with a small screen (ex: 13" Macbook Pro), or resize the browser window viewport to a small height (Below 760px in this case)
• Enter a query/term into the search field (ex: styling) that might result in a large amount of returned results
• View that the bottom of the modal appears to be cutoff

Expected result

I would expect the search modal to have a vertical scrollbar or some other way to reduce the overall height of the modal at smaller screen/browser window sizes.

Actual result

Content underneath the Reference heading appears to be cutoff, and I was unable to see what that additional content/search results might be.

Environment

13" Macbook Pro macOS Sierra v10.12.6 1280x800 resolution Google Chrome v67.0.3396.99

[m-allanson]

That would be great @wuweiweiwu!

[wuweiweiwu]

@m-allanson I’d be willing to pick this up!