Accessibility fix: Allow iOS browsers to auto-scale fonts based on user preference

[chrislachance]

May be a good idea add font:-apple-system-body to the HTML element CSS to allow iOS browsers to auto-scale font sizes based on user preference set in Accessibility > Display & Text size.

See this Codepen for the full code example. https://codepen.io/chrislachance/pen/OJpmgrM

(PS: iOS is set to a default of 17px instead of the browser-standard 16px when using this method.)