Refactor HTML to use CSS grids for table-like layouts

[Phrancis]

Based on a chat conversation it was suggested to use CSS grids, instead of a <div>-based table-like structure (or an actual <table>-based design, which the original HTML Client has).

The primary sections that will benefit from this are

• Lobby/Chat
• Deck Builder
• Possibly the game board, although a flexbox design may turn out to be more appropriate

[Phrancis]

I believe implementing this will also fix this: #121

[Phrancis]

This still needs to be done, but in new Vue.js implementation #144