Recently my company made a fork for a site theme which uses Adobe Source sans Pro as its default font. We need to use cyrillic as well as latin font shapes on our site. For some reason my browsers (Chrome and Firefox) display cyrillic letters in default sans serif fonts (Arial and Deja Vu Sans correspondingly). Cyrillic support was added to Source Sans Pro about a year ago and I believe I have recent version installed on my system. I checked this with my LibreOffice Writer text editor: I set the font and tried both set of shapes, cyrillic shape is in proper accordance with latin one.
Can someone advice on why web browsers do not render cyrillic shapes of Source Sans Pro?