To ensure that a website can be displayed by the most browsers and, therefore, read by the most people it must conform and be validated against the following standards as defined by the W3C:
This guarantees that a website is viewable by any standards-compliant browser such as Google Chrome, Firefox or Internet Explorer. In addition, and depending on the target group for your website, support for older browsers can be provided via workarounds such as the HTML5 shim.
Adjusting for different screen sizes must be done using media queries.
The W3C recommends that browsers and websites respect the user's choice of font size for all websites. This can be achieved by using relative sizes so that elements are relative to the user's preferred standard font size.
Using relative sizing
The standard font size, e.g.12 px, can also be written as 75% or 0.75 em.
When using relative sizing the following rules should be followed:
Graphical text may not be used as it will not reflect the user’s font size.
Elements containing text should have their height set relative to the font size. This preserves the layout but allows larger text to be used.
If horizontal elements are also relatively sized then inline images must also be relatively sized.
It is strongly recommended not to use frames. If frames or iframes are used, only the content frame should be scrollable and a print function for the content frame is required.
Any specific requirements for the website such as plugins or programs for viewing particular content should be listed on a "Technical Details" page.