Use CSS just in webkit based browsers

[axmax2u]

I have the next CSS code:\[code\]#mgheader .letters { display: inline-block; margin-left: 55px; margin-top: -45px; position: absolute;}#mgheader .letters { display: inline-block; margin-left: 10px; position: absolute;}\[/code\]Now I want to execute the first just in Google Chrome and Safari, and the second in other browsers.I tried this, but second code seems to be executing always:\[code\]@media screen and (-webkit-min-device-pixel-ratio:0) { #mgheader .letters { display: inline-block; margin-left: 55px; margin-top: -45px; position: absolute; }} #mgheader .letters { display: inline-block; margin-left: 10px; position: absolute;}\[/code\]How can I fix that?