[Frontend] Welcome modal doesn't resize vertically with screen

[s-egge]

Describe the bug
The Welcome modal that is displayed when entering the website for the first time does not scale vertically based on the screen size or allow scrolling down to see the whole modal.

To Reproduce
Steps to reproduce the behavior:

1. Open a private browser (or clear history for https://app.electricitymaps.com/map)
2. Go to https://app.electricitymaps.com/map
3. Make browser window smaller vertically
4. See error

Expected behavior
I expected the Welcome modal to either resize or the page to allow me to scroll so that the rest of the modal would come into view.

Screenshots

Desktop (if relevant):

• OS: Windows 10
• Browser: Firefox and Chrome