diff --git a/package.json b/package.json
index bb0e6d942..40af61acd 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "react-vant",
-  "version": "0.0.20",
+  "version": "0.0.21",
   "description": "React Mobile UI Components base on Vant UI",
   "repository": "https://github.com/3lang3/react-vant.git",
   "main": "lib/index.js",
diff --git a/src/flex/demo/index.tsx b/src/flex/demo/index.tsx
index 60e2d6c05..f4fcdb8f8 100644
--- a/src/flex/demo/index.tsx
+++ b/src/flex/demo/index.tsx
@@ -8,7 +8,7 @@ export default (): React.ReactNode => {
   return (
     <DemoSection>
       <DemoBlock title="基础用法">
-        <Flex>
+        <Flex justify="center" align="center">
           <Flex.Item span={12}>span: 12</Flex.Item>
           <Flex.Item span={12}>span: 12</Flex.Item>
         </Flex>
diff --git a/src/styles/themes/default.less b/src/styles/themes/default.less
index 001f7f2e5..07836bc04 100644
--- a/src/styles/themes/default.less
+++ b/src/styles/themes/default.less
@@ -66,7 +66,8 @@
 @line-height-sm: 18 * @hd;
 @line-height-md: 20 * @hd;
 @line-height-lg: 22 * @hd;
-@base-font-family: PingFangSC-Semibold, PingFang SC;
+@base-font-family: -apple-system, BlinkMacSystemFont, 'Helvetica Neue', Helvetica, Segoe UI, Arial,
+  Roboto, 'PingFang SC', 'miui', 'Hiragino Sans GB', 'Microsoft Yahei', sans-serif;
 @price-integer-font-family: Avenir-Heavy, PingFang SC, Helvetica Neue, Arial, sans-serif;
 
 // Animation