Sometimes I need to start a gradient at a point past 0% or stop it before 100%. Would it be possible to add support for this? For example, a gradient such as: ``` linear-gradient(to bottom, rgba(0, 0, 0, 0.5) 0%, rgba(0, 0, 0, 0.5) 25%, rgba(0, 0, 0, 0) 100%) ```