If you want your website or application to be usable for older adults and people with specific impairments, there are a set of rules to follow. Even though there are general principles that guide designers’ choices, each case has its particularities. Therefore, one of the things the HCI team can do for you is to analyse the requirements, analyse the target audience and the contexts of use and produce detailed style guides which will guide you on the use of design patterns, colours, fonts, widgets and so forth.