Pull in bookmark icon in a less intrusive way

[longhotsummer]

Currently (see #4) we pull in the bookmark icon when decorating internal refs by linking to the entire fontawesome CSS.
There's got to be a cleaner way to do this that doesn't trample on any existing fontawesome icons used in the site.

Is there a better way to do this? We can pull in an SVG from fontawesome, can we easily inject that into CSS using :after etc.?

[longhotsummer]

We can use this SVG directly in CSS and not pull in everything:

.whatever::before {
  display: inline-block;
  content: "";
  vertical-align: -.125em;
  background-image: url("data:image/svg+xml,<svg viewBox='0 0 16 16' fill='%23333' xmlns="http://www.w3.org/2000/svg"><path d="M2 2v13.5a.5.5 0 0 0 .74.439L8 13.069l5.26 2.87A.5.5 0 0 0 14 15.5V2a2 2 0 0 0-2-2H4a2 2 0 0 0-2 2z"/></svg>");
  background-repeat: no-repeat;
  background-size: 1rem 1rem;
}