style: fix box sizing styles.

Author: jaywcjlove

src/index.less

@@ -34,5 +34,6 @@
     right: 0;
     top: 0;
     bottom: 0;
+    box-sizing: border-box;
   }
 }

website/App.tsx

@@ -1,5 +1,5 @@
 import MarkdownEditor from '../';
-import '@uiw/reset.css/reset.less';
+import '@uiw/reset.css';
 import React, { useState } from 'react';
 import DocumentStr from '../README.md';
 import styles from './App.module.less';