Better dark mode tint on Firefox

[fregante]

In v2 there's a slight mismatch in color in Firefox:

Which is weird since I already have some code to do this:

webext-base-css/webext-base.css

Lines 78 to 84 in 49bd32c

	@-moz-document url-prefix('') {
	@media (prefers-color-scheme: dark) {
	:root {
	background-color: #23222b;
	}
	}
	}

[fregante]

Ah it's being overridden by

webext-base-css/webext-base.css

Lines 86 to 95 in 545ea3c

	/* iOS/iPadOS-specific style */
	@supports (-webkit-text-size-adjust: none) {
	@media (prefers-color-scheme: dark) {
	:root {
	/* Safari iOS has a black background */
	background-color: #1e1e1e;
	}
	}
	}