In our modern era, it is imperative that your website be up-to-date with web standards, or suffer consequences. For instance, Google now punishes web sites that are not mobile-friendly. The old solution was to create a separate website to cater to small screens, but that doesn't work now with countless devices with every size imaginable.
As a result, Responsive Web Design (RWD) was formed to automatically adjust the site content to fit any screen size. There are no rules as to the screen widths, some smartphones are lower in resolution, while the newer tend to have higher resolutions. As such, your web site should be designed to accommodate any size, rather than specific widths for specific devices.
All sites that we design take this in to account and scale properly. We test the site usability across several devices to ensure cross-browser compatability, and also try to make sure your site will still look good on even the outdated browsers which some users cling to or found within corporate offices.
Do you already have a design and need it updated to be Responsive? Have you received a notification from Google that your site is not mobile-friendly? We can convert your existing design as well, often without changing anything but your CSS file.