I created a vector graphic in Illustrator CC and used "Save for Web" to create a transparent PNG of it. When rendered on my site, though, it adds a faint light outline around the gray circle in the included sample screenshot. Notice, though, that it only appears if the image is changed in size (made its container smaller, so the image scaled down).
Image at 100%, no white outline - nice and crisp:
Image scaled down to 95% (or any % besides 100), artifact outline that makes it look blurry:
I've never had this issue before and have tried adjusting the artboard to whole px amounts, removed the color profile, changed the raster transparency settings, switched between cmyk and rgb color modes, unchecked convert to sRGB, and a multitude of other tweaks I'm forgetting at the moment, but this is pretty frustrating and I'm hoping this wonderful community can provide some insight.