I was wondering if the html tag:
<link rel="stylesheet" href="template/style.css">
Can the stylesheet be loaded correctly on feature phones?
Like Quentin says, it depends on what's in the stylesheet. Feature / dumb phones have varying CSS support, so you'd need to do a bit of research. Something to get you started:
A list of CSS3 properties Nokia's Symbian browser can support. Sure there's a lot more stuff like this floating around. If you didn't already know, Symbian's an OS used on phones such as the N95 (last non-smartphone I owned)
Unfortunately stuff like media queries that you'd use for modern responsive design are often pretty shaky on these platforms from my experience. Hope that helps!