Resolve assets path start with '/' need to relative current project path. Add static css url resolves.

lib/index.js

@@ -1,5 +1,6 @@
 var Assets = require('assets');
-var dirname = require('path').dirname;
+var p = require('path');
+var dirname = p.dirname;
 var functions = require('postcss-functions');
 var postcss = require('postcss');
 var quote = require('./quote');
@@ -23,6 +24,15 @@ function formatHeight(measurements) {
   return util.format('%dpx', measurements.height);
 }
 
+// Normalize css assets path, resolve to project base if start with '/'
+function normalizePath(path, options) {
+  var normalizedPath = unquote(unescapeCss(path));
+  if (normalizedPath.charAt(0) === '/') {
+    normalizedPath = p.resolve(options.basePath || '.', normalizedPath.slice(1));
+  }
+  return normalizedPath;
+}
+
 function plugin(options) {
   var params = options || {};
   var resolver;
@@ -46,6 +56,10 @@ function plugin(options) {
       });
   }
 
+  function resolveUrl(path) {
+    return resolver.url(normalizePath(path, resolver.options)).then(formatUrl);
+  }
+
   return postcss()
     .use(function appendInputDir(css) {
       var inputDir;
@@ -67,24 +81,22 @@ function plugin(options) {
     })
     .use(functions({
       functions: {
-        resolve: function resolve(path) {
-          var normalizedPath = unquote(unescapeCss(path));
-          return resolver.url(normalizedPath).then(formatUrl);
-        },
+        url: resolveUrl,
+        resolve: resolveUrl,
         inline: function inline(path) {
-          var normalizedPath = unquote(unescapeCss(path));
+          var normalizedPath = normalizePath(path, resolver.options);
           return resolver.data(normalizedPath).then(formatUrl);
         },
         size: function size(path, density) {
-          var normalizedPath = unquote(unescapeCss(path));
+          var normalizedPath = normalizePath(path, resolver.options);
           return measure(normalizedPath, density).then(formatSize);
         },
         width: function width(path, density) {
-          var normalizedPath = unquote(unescapeCss(path));
+          var normalizedPath = normalizePath(path, resolver.options);
           return measure(normalizedPath, density).then(formatWidth);
         },
         height: function height(path, density) {
-          var normalizedPath = unquote(unescapeCss(path));
+          var normalizedPath = normalizePath(path, resolver.options);
           return measure(normalizedPath, density).then(formatHeight);
         }
       }