Font-size randomly switching on ios

I have done an application that does everything I want, but Im facing a problem :
the font-size on ios is inconsistent even same things have not the same size. I have tried this :

  @media screen and (max-device-width: 480px){
      -webkit-text-size-adjust: none;

but nothing seems to work, I read some topics about this subject without success, it’s too late for me to switch for an other tool to do this app. So if someone can be my Prince Charming… I would be very grateful.