Sticky header on all devices

Hello,

First of all, thank you for the great theme and the support. I appreciate!

I have one issue with the sticky header. I intend to use a one page menu and for that I need to have it work always on all devices. I have been using this code:

@media only screen and (max-width: 989px) {
.responsive #top #wrap_all #header {
    position: fixed;
background: white;
}
.responsive #top #main {
    padding-top: 131px !important;
}
}

However, on (an admittedly old) iPad the header does not stick. So I am wondering whether I can simply determine that I want the header to stick always (whether it is a smartphone, tablet, computer).

Thank you,

Christian