Hi There,
I am on PC and can not replicate that issue. So I assume this is only happening on iOS devices (iPad, iPhone, etc.)
Please add this on top of your Custom CSS on Customizer.
a[href^="tel"] {
color: #fff !important;
text-decoration: none !important;
}
Don’t forget to clear your phone’s browser cache before previewing it.
And then check your entire custom CSS here: http://csslint.net/ and address all the errors.
Thanks.