vaadin8 - bourbon library font file not found

Question

We have own custom theme base valo. Why search vaadin our custom font in value util directory?

404 GET /VAADIN/themes/valo/util/bourbon/css3/fonts/our-font-name.eot 

What is the reason for that?

outcustomtheme.scss:

'../../../../assets/sass/core/...

they are our custom sass styles

 @import '../valo/valo';
    @import '../../../../assets/sass/core/base/base';
    @import '../../../../assets/sass/core/variables';
   ....
    @import '../../../../assets/sass/core/system/system-notification';
    @import 'fonts/neg/css/animation';
    @import 'fonts/neg/css/neg-embedded';
    @import 'fonts/neg/css/neg-ie7';
    $v-included-components: window,
    tabsheet,
    csslayout;
    // $v-included-components: tabsheet;
    @mixin ourthemename {
        @include valo; // Spinner change//
        @include base;
       ....

    }

    @font-face {
        font-family: 'Roboto Condensed';
        font-weight: 400;
        font-style: normal;

        src: url('fonts/rc/rc.eot'); // IE9 Compat Modes */
        src: local('Roboto Condensed'), local('RobotoCondensed-Regular'), url('fonts/rc/rc.eot?#iefix') format('embedded-opentype'), // IE6-IE8 */
        url('fonts/rc/rc.woff2') format('woff2'), // Super Modern Browsers */
        url('fonts/rc/rc.woff') format('woff'), // Modern Browsers */
        url('fonts/rc/rc.ttf') format('truetype'), // Safari, Android, iOS */
        url('fonts/rc/rc.svg#RobotoCondensed') format('svg'); // Legacy iOS */
    }