mermaid render width overflow

```
<code class="language-mermaid">C4Context
&nbsp;&nbsp;&nbsp;&nbsp;title&nbsp;系统上下文图
&nbsp;&nbsp;&nbsp;&nbsp;Person(customer,&nbsp;"客户",&nbsp;"系统的主要用户")
&nbsp;&nbsp;&nbsp;&nbsp;System(banking_system,&nbsp;"银行系统",&nbsp;"处理所有存款业务")
&nbsp;&nbsp;&nbsp;&nbsp;Rel(customer,&nbsp;banking_system,&nbsp;"使用")</code>
```

