纵向字体大小与移动设备的横向字体大小

I am developing a mobile website but have encountered this problem - a font size of 14px is displaying much larger in landscape than in portrait. However, it seems to be based on the fact that the Div size is set to 100% so in landscape it is obviously wider. What I don't understand is why that should affect the size of the font given that 14px isn't a relative size but a fixed one?I am developing a mobile website but have encou