CSS3 opacity gradient?

I am looking to create an effect like this, but my website has a dynamic background-color. Note that this example uses a white overlay, which does not work with different backgrounds.

p {
    width: 300px;
    overflow: hidden;
    height: 50px;
    line-height: 50px;
    position: relative;
}
p:after {
    content: "";
    width: 100px;
    height: 50px;
    position: absolute;
    top: 0;
    right: 0;
    background: linear-gradient(90deg, rgba(255,255,255,0), rgba(255,255,255,1));
}

What I was hoping to do was to set up a CSS opacity gradient. This sort of works, but the code is too messy. Looking at this second example, I could implement it in jQuery, but is there any way to do this entirely in CSS?