The IMSLP website is designed for desktops and difficult to use on a touchscreen mobile device, chromebook, or tablet. Would there be significant interest in having something that is designed specifically for a web browser, with good touch gesture friendliness, and not necessarily needing to download the entire PDF locally?
Here's a very crude, not-not-yet-functional, idea of what I'm potentially talking about.
After the install itunes on windows 7 when I tried running the application I encountered with the HTML 5 interface error adn that is why the application was not opening at all.