CSS Font Border?

There’s an experimental CSS property called text-stroke, supported on some browsers behind a -webkit prefix.

h1 {
    -webkit-text-stroke: 2px black; /* width and color */

    font-family: sans; color: yellow;
}

<h1>Hello World</h1>

 Run code snippetExpand snippet

Another possible trick would be to use four shadows, one pixel each on all directions, using property text-shadow:

h1 {
    /* 1 pixel black shadow to left, top, right and bottom */
    text-shadow: -1px 0 black, 0 1px black, 1px 0 black, 0 -1px black;

    font-family: sans; color: yellow;
}

<h1>Hello World</h1>

 Run code snippetExpand snippet

But it would get blurred for more than 1 pixel thickness.