Unfortunately, web browsers do not support OpenType layout features (yet). But the TPTQ Arabic webfont system generates font files on the fly, and can apply OpenType features directly to the file in the process. This enables us to support true small caps as well as various styles of numerals. You can control these advanced OpenType features via your online account.
Don’t use the font-variant:small-caps; property in CSS, as this scales the characters mathematically, rather than using true small caps.