Why doesn't CHM display a custom font?

Question

Electronic books

Hello everyone,
we are building CHM from HTML files that use the custom font Suisse Int'l -
body { font:20px/1.4 "Suisse Int'l", Arial, Helvetica, sans-serif; padding: 0 24px }
If the font is set, the text should be rendered in Suisse Int'l. And in browsers, including Internet Explorer, everything is so.
However, after building in CHM, what do we see? We see Arial! Why is that? What doesn't he like about our CSS?