:lsat-child typo in app.html CSS

[mstange]

There's a typo in one of the progress CSS rules:

learn.svelte.dev/content/tutorial/common/src/app.html

Lines 182 to 189 in 7bf2069

	progress:first-child {
	margin-top: 0;
	}
	progress:lsat-child {
	margin-bottom: 0;
	}