Just so you know the iPhone 6 lies about it's min-width. It thinks it is 320 instead of 375 it is suppose to be.
@media only screen and (max-device-width: 667px)
and (-webkit-device-pixel-ratio: 2) {
}
This was the only thing I could get to work to target the iPhone 6. The 6+ works fine the using this method:
@media screen and (min-device-width : 414px)
and (max-device-height : 736px) and (max-resolution: 401dpi)
{
}