Responsive Design: is the layout of a website so it adapts automatically to the screen size of any device from desktops and laptops to tablets and smartphones.
Litmus reported that 48% of email is opened on a mobile device (Email Analytics Jan 2015). With such a high percentage of opens through mobile devices, you want to make it as easy as possible for your constituents to read your communications. Whether it's your website, donation &/or volunteer page, emails, newsletters, etc., please ensure that these are RESPONSIVE. If your constituents need to pinch in and pinch out any communications opened through a mobile device, chances of engagement are pretty slim.