Increase Popup Max-Width to 600px

[jdalt]

What

This PR increases the max-width of the popup to 600 pixels.

Why

This looks much better on larger screens. Originally the small 275px width was used because scrolling was difficult.

Ensure the following interactions work as expected. Please test using a mobile form factor.

• [ ] Tapping on a marker on the map displays information about the marker in a popup.
• [ ] Tapping the "Show list of locations" button replaces the map view with a list view.
• [ ] Tapping an item in the list replaces the list view with a map view, and navigates the map to the tapped item on the map.
• [ ] Tapping one of the ✅'s in the legend filters items on the map and in the list.
• [ ] Changing the language to spanish changes things on the page.
• [ ] Clicking the Help/Info button opens and closes a menu with information.
• [ ] Clicking the X Close button on the Help/Info screen closes the modal.

Check the app in the following web browsers:

• [ ] Chrome
• [ ] Firefox
• [ ] Edge
• [ ] Safari

[jdalt]

We're going to try and go in the direction of a modal.