Unfortunately, I am one of “those” individuals for which dark mode does not work. This is true for both Obsidian your product and Obsidian your web site (why don’t you have a published email address for reporting problems with your side???). So, please consider this a request to add options to both your web site and to your product to turn off persistent dark mode. Thanks.
In the app, in settings > appearance, you can change to light mode.
I prefer light mode for writing.
This forum is the place to report problems.
The website isn’t really in dark mode, it just has a dark aesthetic. @austin has provided the right instructions for ensuring the app stays in light mode.