Dark mode button and alert modal

[euotiniel]

I've been thinking about repositioning the dark mode button.

Maybe something more elegant, like putting it in a header or over the phrase Emoji Palette and obviously changing the text to a button with icons.

What do you think about it?

As for the model, you could use something more elegant instead of the standard browser alert.

[anubra266]

Thanks @euotiniel. Feel free to open a PR.