Adds automatic CSS zoom for Explore/Validate pages

[misaugstad]

#303 is the issue we're working on here. This is a temporary fix because it doesn't work for Firefox.
Resolves #2535 as well

Adds automatic zoom on the Explore and Validate pages using the CSS zoom property instead of browser zoom. This doesn't work on Firefox. I've tested that it works on Chrome and Safari thus far, so that's all I've enabled. I'll test it on Edge in the next couple of weeks and enable it there if it works well too. Everything below the navbar gets zoomed.

I also removed the footers on both of those pages, which makes the app take up basically the entire screen with no scrolling ever happening on the page. Easy enough to add the footers back in, but I really like how it looks/feels with no scrolling.

Before/After screenshots (if applicable)

Before (80% zoom)

After (80% zoom)

Things to check before submitting the PR

• I've written a descriptive PR title.
• I've added/updated comments for large or confusing blocks of code.
• I've included before/after screenshots above.
• I've updated any logging. Clicks, keyboard presses, and other user interactions should be logged. If you're not sure how (or if you need to update the logging), ask Mikey. Then make sure the documentation on this wiki page is up to date for the logs you added/updated.
• I've tested on mobile (only needed for validation page).