From your other responses, this is a system issue not a problem with the website.
Lemmy.world’s code has this font list for sans-serif: system-ui,-apple-system,“Segoe UI”,Roboto,“Helvetica Neue”,“Noto Sans”,“Liberation Sans”,Arial,sans-serif,“Apple Color Emoji”,“Segoe UI Emoji”,“Segoe UI Symbol”,“Noto Color Emoji”
I’d use the dev tools to check which font is being rendered. I’m on Windows so I get Segoe UI, which I find entirely acceptable.
cURL is a very commonly used program to download individual files from the command line and worth installing to have it around in the future.
sudo apt update
sudo apt install curl
The first command tells your package manager to update its list so you ask for the latest version. You can skip it if you’ve already updated today. The second command tells your package manager to install cURL.
This will happen every now and then, especially when building a package from source. You won’t have some common utility that the documentation writer assumed you had, and you will need to find what package provides it and install the package.