Webkit browsers support the ability to add “stroke” to fonts. This bit of style makes fonts look thinner (assuming a white background):
-webkit-text-stroke: 2px white;
Example on codepen here: http://codepen.io/mackdoyle/pen/yrgEH
Some people are using SVG for a cross-platform “stroke” solution: http://codepen.io/CrocoDillon/pen/dGIsK