Hype adds the those properties as inline CSS, so if you are using rules from a <style> tag you’ll need to add !important after the font-family and font-weight in order for that style to override.
<style media="screen" type="text/css">
.vitesse-book {
font-family: "Vitesse A", "Vitesse B" !important;
font-style: normal !important;
font-weight: 400 !important;
}
.vitesse-bold {
font-family: "Vitesse A", "Vitesse B" !important;
font-style: normal !important;
font-weight: 700 !important;
}
</style>
If the weights themselves were exposed as different font-family names (maybe that’s what A and B are?) then you could add them separately as Custom CSS fonts within Hype’s Add More Fonts… panel and use them like any other font. Otherwise this is the best that can be done. (I’d like to improve how Hype deals with weights in the future…)