Light mode doesn't persist on navigation/refresh

[samcunliffe]

Describe the Bug

When browsing the website in light mode, the theme switches on every refresh.

To Reproduce

Switch to light mode and refresh the website.

Expected Behaviour

The website stays in light mode.

Actual Behaviour

The website switches theme back to dark mode.

Additional Context

- Operating system: Tested in Chrome Android/mobile and Firefox on Mac.