For example, when choosing a pair of typefaces to combine in a single line, it is advised that:

  • they are from different categories, in order to make them contrast
  • they should have the same x-heights, in order to make them smoothly reading

(How to know which second typeface should be used, given a contextual typeface?)

I wonder, what if the difference in x-height would be contrast enough, yet the smoothly reading requirement is still satisfied? Therefore, even if the pair come from the same category and it's a no-no, it would become insignificant or even unaffected to the viewer's eyes? How to make such thing happens?

closed as primarily opinion-based by Zach Saucier, Westside, Scott, Luciano, Paolo Gibellini Mar 6 '18 at 11:13

Many good questions generate some degree of opinion based on expert experience, but answers to this question will tend to be almost entirely based on opinions, rather than facts, references, or specific expertise. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 4
    Graphic design is more of an art than a science. Rules are there to be broken. – Westside Mar 6 '18 at 6:17
  • 1
    "Rules? We don't need no stinkin' rules!" (overheard on a Bolivian trip to a design conference) -- The reality.. guidelines are guidelines not end of the world mandatory requirements. Break them whenever a design works better without them. – Scott Mar 6 '18 at 6:26
  • To be clear: your example using typography is only an example? You're mostly interested in the larger question? – Zach Saucier Mar 6 '18 at 8:14
  • @ZachSaucier yes. Would it be too broad? – Ooker Mar 6 '18 at 8:16
  • @Scott does this mean different designers will have different opinions on the same design? – Ooker Mar 6 '18 at 15:51