use -webkit-animation case image Edge blur

when i use -webkit-animation to Flashing an image ， case all image in this web case Edge blur

same page work well in andriod web Browser
**********css file ************

@-webkit-keyframes twinkling{
0%

{ opacity:0; }

100%

{ opacity:1; }

}
.flash_1s{
-webkit-animation: twinkling 1s infinite linear;
}