In Firefox, select the options button under the hamburger menu, Pick the Content tab in the sidebar. Under fonts and colors click Advanced, Under Text Encoding, pick the Fallback Text Encoding. Other includes Western European.

Shakurazz said

Lithuanian-specific characters appear differently than the rest in Firefox and IE, but not Chrome. Chrome uses Western (Windows-1252) character encoding, while Firefox and IE use Unicode. Take a look at characters with diacritics in the attached image: All such characters are not bold: https://www.youtube.com/user/LRTinklas/videos

Alternatively, Press ALT and from the menu that appears select View and then under Text Encoding pick Western

I forgot to mention that I tried to choose Western, but then these characters become hieroglyphs. They just lack bold.

Shakurazz said

I forgot to mention that I tried to choose Western, but then these characters become hieroglyphs. They just lack bold.

So you specifically need Western (Windows-1252)?

I don't know. In Chrome settings Windows-1252 is specified as encoding set. I don't know what version of Western is the Firefox one, it doesn't say.

Too bad there isn't an Edit feature in this forum. Now Chrome says that it uses Unicode (UTF-8). Maybe there is a problem with my fonts.

Is the same font used for all those characters?

You can right-click and select "Inspect Element" to open the Inspector (Firefox/Tools > Web Developer) with this element selected. You can check the font used for selected text in the Font tab in the right pane of the Inspector.

• https://developer.mozilla.org/Tools/Page_Inspector

Yes, it says Roboto medium (remote) and Arial (system)

I solved the problem by downloading the Roboto font family from here and installing it in my PC.