fix bg in lib

lib/css/base.css

@@ -118,7 +118,7 @@ a {
   bottom: 0;
   left: 0;
   overflow: auto;
-  background: #fff;
+  background-color: #fff;
   -webkit-transition-property: top, bottom;
           transition-property: top, bottom;
   -webkit-transition-duration: .2s, .2s;

lib/css/forms.css

@@ -32,7 +32,7 @@ input[type="color"],
   height: 40px;
   padding: 10px;
   margin-bottom: 10px;
-  background: #fff;
+  background-color: #fff;
   border: 1px solid rgba(0, 0, 0, .2);
   border-radius: 3px;
   box-shadow: 0 1px 1px rgba(255, 255, 255, .2), inset 0 1px 1px rgba(0, 0, 0, .1);