Code Review is the only website on which font weights behave weirdly - for me (using Linux Mint 18.2 and Firefox 55):
Some bold text: hello world.
... but it doesn't seem bold! It's the same weight as the rest of the text.
Level 1 heading
Level 2 heading
Level 3 heading
the heading text has regular weight (unlike the norm on SX website), while the source code snippets in headings - is in bold.
I'm not the only one seeing this, right?
Screenshot of the above: