Like many front-end devs, I've been using the border trick to render triangles in CSS. http://apps.eky.hk/css-triangle-generator/ this generator helps with the technique. Today, like every week (almost), the Firefox team released a new version without any clear changelog on the rendering engine. Now we can see an ungraceful gray border around those triangles. I haven't found a trick to get rid of it yet. On top of that, before Firefox 17, when people were complaining about how aliased those triangles looked, an additional trick was to set the border-style property to "dashed" instead of solid. Using firebug on the triangle generator, you can quickly see how it shows up now, and cry yourself to death. I hope a more brillant front-end dev than myself will find a fix for this and share it here. Thanks