Preface
When the designer asked me what is the font of some text I told her to press F12 and check the font-family in Computed, like this:

Main
However, when I am using that font-family I find that I was totally wrong. The actual font the text used is this:

That is totally different from the font-family though I know that we can’t be sure that the browser would use the font-family we set in css.