I put quite a lot of work into getting st and ct (optional) ligatures into the Linux Libertine typeface. And, turned them on by default in my copy. And, I have

I put quite a lot of work into getting st and ct (optional) ligatures into the Linux Libertine typeface. And, turned them on by default in my copy. And, I have my browser set to use Linux Libertine for all text, whether "serif", "sans", or whatever the page server said it ought to be. (Button wingdings something look odd.) So, I don't see anything odd on the page, but I do see "st" ligatures. Just not theirs. On my phone, where even Firefox utterly refuses to use the fonts it is directed to, I see ligatures in the sans-serif font, which is just ugly. But they do not make the sans-serif any worse than it always is.