Wrap the summary items inside only a ul and li items (removing a div)

[pattonwebz]

This PR removes a wrapper div, making summary items be <li> elements only so they are read out correctly to a screen reader.

The styles were tweaked to use CSS grid for styling. There are some minor differences after the style changes.

[pattonwebz]

@SteveJonesDev I swapped it to use the lg breakpoint as the one that swaps it to the 2 col layout instead of the md breakpoint.