Mixed HDR/SDR content is interesting problem. To me the example where thumbnail is presented with HDR color feels wrong, because it makes the thumbnail to stand

Mixed HDR/SDR content is interesting problem. To me the example where thumbnail is presented with HDR color feels wrong, because it makes the thumbnail to stand out in a distracting way and seems highlighted in some way. But the iPhone example on the other hand looks really good; note how it seems like it switches from SDR to HDR display when the picture is selected. For desktop, maybe the simplest heuristic for choosing HDR/SDR is if the the window is fullscreen/maximized or not.