Fix initial toggle if default light mode

[michaelkacher]

Resolved an issue where on first load of the page when default prefersLight mode is true, the toggle button would be in the incorrect mode.

Scenario:

• Have default OS set to light
• load the page, ensure local storage is cleared, if not clear it and refresh

Result:

• Toggle button looks like the sun and if you click it, you stay in light mode

Expected:

• Toggles to dark mode

[mattjennings]

Oh right on, thanks for the PR!