We always build for mobile first and then only desktops. This is because traffic to websites have exceeded that of desktops and is set to grow even more as mobile connectivity speeds get higher and phones increase in processing power.
Even Google has moved to a Mobile-First Indexing where it predominantly uses the mobile version of the content of a website for indexing and ranking. In the past, it used to index the dekstop version to eavluate the relevance to a user’s search query.Today, it’s all about how good an experience your mobile site is. Apart from design and user experience, there are many other different factors that go towards creating a good Mobile Experience for ranking and ultimately, engagement and sales. We then test the website for the different mobile platforms and device types to ensure that the experience is optimised across the board.