Adjust unit output

Author: mgreter

src/units.cpp

@@ -334,10 +334,21 @@ namespace Sass {
       if (i) u += '*';
       u += numerators[i];
     }
-    if (nL != 0) u += '/';
-    for (size_t n = 0; n < nL; n += 1) {
-      if (n) u += '*';
-      u += denominators[n];
+    if (iL == 0) {
+      if (nL > 1) u += '(';
+      for (size_t n = 0; n < nL; n += 1) {
+        if (n) u += '*';
+        u += denominators[n];
+      }
+      if (nL > 1) u += ')';
+      if (nL != 0) u += "^-1";
+    }
+    else {
+      if (nL != 0) u += '/';
+      for (size_t n = 0; n < nL; n += 1) {
+        if (n) u += '*';
+        u += denominators[n];
+      }
     }
     return u;
   }