Disable night mode?

When my phone switches to night mode (when it’s dark outside), certain elements of my site turn black. But any images still have a white background, and the text isn’t readable whatsoever.

How can I disable night mode for my site? I don’t mean just click the night mode button — I mean override a device’s night mode settings so my site never changes colors (always white background)?

The page I need help with: [log in to see the link]