A website is viewed through a browser on a device of some kind. There are many types of browsers available and an uncountable number of devices, all with a different sized screen and resolution. Taking this into account, it would be impossible to design a website for every single one of these permutations. So today, designers and developers like to design and build websites that are 'responsive'.
For our designers, this means not designing a site that looks great in one particular fixed size. Instead, designing a site layout that can adjust and change to look perfect no matter what height or width the browser or screen is.
Usually Arc likes to design for the smallest screen size first. Then add complexity to the design as the size expands and provides more space. This is certainly easier than designing big, then trying to subtract and remove elements as the size shrinks and contracts while trying to maintain that design that was so good earlier!
Now it doesn't matter if you view on a tablet or a desktop, a phone or a laptop... We know our site looks good at any size on any screen.
For our developers, turning that design into a 'responsive' site is a case of taking advantage of the basic nature of Cascading Style Sheets (CSS). We simply write style rules for the smallest size site first then 'cascade' any new rules needed for anything that changes as the screen size grows.
A common question is 'Can you make our site look good on a phone or tablet too?' and the reality is, if the site is responsive, it is designed to look good on your phone and tablet before any consideration is made about larger sized devices.