This grid template is optimized for mobile Android devices. The most common mobile screen size of 360px wide. I made the template extra tall because it is common to have tall layouts on small devices.
This grid template is optimized for tablets in the portrait view. Targeting 1024px X 768px commonly seen on an iPad.
This grid template targets desktop computers with a max breakpoint of 1200px wide. I made the template 1900px wide so you could see how your design looks on the most common browser size with the large left and right margins.