Sometimes you need to apply CSS rules to deal with Webkit browsers such as Safari and Chrome. One example: sometimes non-standard fonts rendered using @font-face or an embed service such as Typekit or Google webfonts display thinner than on other browsers.
You can deal with this using a media query:
@media screen and (-webkit-min-device-pixel-ratio:0) {
body { font-weight: 400; }
}
Thanks to phrappe.com for this useful tidbit!