High
This Hint is very important, and definitely warrants attention.
Issue
This Hint represents an error or problem that needs to be fixed.
Font size is too small for mobile devices
This means that the URL in question contains some text which is too small, and therefore not legible for mobile devices.
Why is this important?
If the font size is too small, it makes it difficult for mobile users to read, causing them to zoom and scroll. It is recommended to use a base font size of 12 CSS pixels on the <body> or <html> tag, anything smaller is considered illegible.
What does the Hint check?
This Hint will trigger for any internal URL for which a viewport is set, and contains fonts smaller than 12 CSS pixels.
How do you resolve this issue?
Adjust your CSS to ensure that all fonts are over 12 CSS pixels. You may feel that 12 pixels is still too small, so check readability on smaller viewports using Chrome DevTools and other emulation tools.