You could easily let your website address users with settings at higher zoom levels by including a media query like:
@media only screen and( -webkit-min-device-pixel-ratio: 1.25 ),
only screen and( -o-min-device-pixel-ratio: 5/4 ),
only screen and( min-resolution: 120dpi ),
only screen and( min-resolution: 1.25dppx ) {
body {
font-size: 1rem;
}
}
See this article for an extended explanation and why the cleaned up solution of the media query is sufficient for a broad browser support: IE9+, Fx3.5+, Opera9.5+, Webkit Browsers Chrome and Safari, both Desktop and Mobile.