Collors show up wrong on iphone

Hello, i hope someone can help me cause i have this weird thing going on… my site collors of text and backgrounds looking okay on pc (windows) and andriod devices but on a iphone the collors of text in general and on button show up in a very dark collor or black and thats incorrect some white text shows up black or a yellow text that show up black … but i realy have no clue how to fix this its only on a iphone device