I've faced the same issue. Well, I was just trying to use a servlet to load welcome jsp page, which contains a .css file in header.
<head>
<link rel="stylesheet" type="text/css" href="css/base.css">
</head>
And I got the same error "Resource interpreted as Stylesheet but transferred with MIME type text/html: "http://localhost:8080/webapp/css/style.css"
When I used developer tools in chrome, under 'Network' tab, two calls were made when hit my webapp's landing url "http://localhost:8080/webapp/"
I changed my default servlet url from "/" to "/index" in web.xml
<servlet-mapping>
<servlet-name>NextServlet</servlet-name>
<url-pattern>/index</url-pattern>
</servlet-mapping>
And then added "./" to href,
<head>
<link rel="stylesheet" type="text/css" href="./css/base.css">
</head>
It worked.