Because it uses modern CSS features, this component will not work in Internet Explorer (at all) or versions of Edge, Firefox, Safari, or Chrome that were released before May 2017 (version details here).
What does this theme component do?
The short version: This takes our standard topic list navigation and puts it into a sticky sidebar (as long as your browser is wider than 768px). You also have the option in the settings to show the sidebar on the right.
The long version: We’ve talked about this layout a little bit on Meta previously (https://meta.discourse.org/t/proposing-a-left-aligned-slide-out-hamburger-menu/30287), and I was curious to see what it would be like to simply move our existing navigation to a sidebar.
To build this I used a combination of grid, flexbox, and a value for
sticky. Sticky is very new to browsers (version support), and as you’d guess, it makes an element sticky on scroll... the nice thing about it is that unlike
position: fixed, it doesn’t take your element out of its existing position in the layout. If your browser doesn’t support sticky, the sidebar simply doesn’t stick.
Keep in mind that since this is a drastic layout change, this component may not be immediately compatible with other themes.