I had the opportunity to work with Mathias for a couple years in 21.co. First indirectly in 21Shares and then directly building BlockSensai. Like any good designer, Mathias has amazing attention to detail and is passionate about the look and feel of every aspect of a product. However, what separates him from other designers is his ability to pursue pixel perfection with the engineers, but also allow them to work quickly and accept trade offs. As anyone can imagine, this is always a constant conversation, but knowing when to push and when to accept is important in all roles and essential between engineers and designers.