GPUs are so effective that an entire ecosystem of specialized languages and environments has grown up around general-purpose computing on graphics processing units (GPGPU) focusing on high performance code. We, though, will focus on portability and instructional design, limiting our discussion to techniques available from within a web browser.
Most of you reading this have probably encountered this image at least once. It's a joke we can all relate to, right? You try and do something simple with CSS, and the arcane ways in which even basic properties interact inevitably borks it up.