Merge pull request #3265 from baiyaaaaa/select

fix select style problem(#3230)

packages/theme-default/src/select.css

@@ -68,6 +68,10 @@
       }
     }
 
+    & > .el-input {
+      display: block;
+    }
+
     @e input {
       border: none;
       outline: none;