Font CSS styles are not adding

Hi,

I'm trying to apply custom css for font such as family, style, weight, but nothing applied  other than font-family .

Also in Collection widget there is scroll by default, is there any way to customize the scroll.

.imgLabel{
font-family: "Montserrat", sans-serif;
font-weight: semi-bold 600 !important;
}

Kindly let me know how to apply css on fonts and for scroll in collections.

Thanks in advance