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Hard to tell what to do without seeing specifically where this error is coming up, but it usually has something to do with font sizes being too small on mobile devices. Mobiles have much more densely packed pixels on their screens (images are sharper, the pixels are smaller and more numerous). This means that 12 pixels (font-size) on desktop can look like 5 or 6 pixels on mobile devices (or even smaller) This is why, with responsive design, many people don't specify a pixel-based font-size. They'll make the font size relative (rather than absolute) somehow, be that by calculating pixel width against screen width as some percentage, or by working with newer font-sizing specifications (there are many, and many ways to use them). It's all about inflating font-sizes on devices with more densely packed pixel screens, so that the fonts don't come out looking minuscule Sometimes you can get errors where, even though the site's design is responsive, as someone was writing text in the CMS text editor - it appended styling info including the px font-size, which is then inlined (overruling all your perfectly thought out font-sizing CSS rules) If it's not mobile related at all, it's likely that the font is just generally too small