手机端样式细节调整，补充测试用例 (#3)

* unit test

* picker and dialog unit tes

* fix:quantity and loading

packages/vant-css/src/quantity.css

@@ -4,6 +4,14 @@
   @b quantity {
     font-size: 0;
 
+    @m disabled {
+      .van-quantity__input,
+      .van-quantity__minus,
+      .van-quantity__plus {
+        border-color: #e8e8e8;
+      }
+    }
+
     @e stepper {
       width: 40px;
       height: 30px;