Firefox font issue

Hi,

I have loaded up a font face on my server and its being pulled in correctly on chrome, IE and safari, but not on firefox. I cant see why. Any help?

This is my font face code:

@font-face {
font-family: 'hell' !important;
src: url('https://marondera.co.uk/rock-group/fonts/hell.eot');
src: url('https://marondera.co.uk/rock-group/fonts/hell.eot?#iefix') format('embedded-opentype'),
     url('https://marondera.co.uk/rock-group/fonts/hell.woff') format('woff'),
     url('https://marondera.co.uk/rock-group/fonts/hell.ttf') format('truetype'),
     url('https://marondera.co.uk/rock-group/fonts/hell.svg#helvetica_neueregular') format('svg');
font-weight: normal;
font-style: normal;
}

my demo site is at: https://bit.ly/1oQOPov

Any help would be appreciated. I have tried many things, (smily face, .htaccess etc)

Thanks!