Site should stick with user's choice of light or dark mode

[cdw9]

I'm regularly seeing the site switch to dark mode, and sometimes an in-between version with a dark wrapper and light content. Seen in Chrome and Firefox

Steps to reproduce:

• Go to a page like https://www.boost.io/libraries
• Set the site to light mode
• Right click on a link, and select "Open link in new window"

The new tab will open, and you'll stay on the libraries page. Without doing anything else, the page will switch to dark mode.

Now if you look at the tab you opened, it will be in light mode. If you open another link in a new tab, it will display light mode, but the first link you opened will display dark mode.

I haven't found a way to consistently reproduce the in-between version. The moon displays, but clicking it changes the wrapper to light mode.

[rbbeeston]

This is probably also related to a similar issue where opening the search after changing the theme retains the old theme. Ultimately it's a state issue, and might be better managed on the backend rather than the front-end.

@GregKaleka, your thoughts?

[GregKaleka]

We could handle theming on the backend, though it would require moving the setting from localstorage to a cookie (I believe there's some sensitivity to that for anonymous users).

[GregKaleka]

Also FWIW, I can't reproduce this in Safari (haven't tried chrome or ff).