That is exactly why you cannot design for specific devices because there are now hundreds all at different sizes.resolutions and orientations.
As Chris said the only thing you really need to concentrate on is your design and assuming you have created a fluid design you can test in your browser by simply grabbing the right edge of the browser and dragging it smaller. At some point the design may look awkward or not fit so just before that happens throw in a media query and make it look better.
With a few well placed media queries you can normally make a design go from large to small (320px min). In that way you cater for all devices and orientations now or in the future (apart from devices like the apple watch but that's not really relevant for a website).
You can of course also use specific media queries for landscape and orientation and/or common devices but in essence all you are interested in is the available width in which to show your design. If you design carefully and use a fluid approach you can make the design fit all screens without too much hassle.
There are limits of course to what can be achieved but flexbox (modern browsers only) allows the flexibility to even move items out of order but still remain in the flow.