Just a suggestion, but you may want to consider trapping the keyboard focus when the hamburger menu is displayed. Currently, the menu covers the entire content of the page, but the user can still tab through to the page elements beneath it; they just don't know what they've tabbed through to because they can't see it. Also, the labelling could be a bit better on the dark mode and hamburger buttons to indicate to the user what the buttons do, as those sorts of things are the least likely to be changed by anyone using what you've provided here as a base.
Just a suggestion, but you may want to consider trapping the keyboard focus when the hamburger menu is displayed. Currently, the menu covers the entire content of the page, but the user can still tab through to the page elements beneath it; they just don't know what they've tabbed through to because they can't see it. Also, the labelling could be a bit better on the dark mode and hamburger buttons to indicate to the user what the buttons do, as those sorts of things are the least likely to be changed by anyone using what you've provided here as a base.
Thank you very much for pointing out such an important issue.