title: how to customise the bg-color of the menu in elementUI
body: <p>In elementUI the default background-color is white ; when choosing the them:dark , it is black, but how can I customise the bg-color by myself?
  I have tried to add the style property at the el-menu tag , but it didn't work</p>
  
  <pre><code>&lt;el-menu style="{background-color: rgb(36,36,36)!important}" 
  </code></pre>
  
  <p>I try to find the source code of the css file of el-menu tag and I try to change some setting relating to background-color, don't work either</p>
  
  <p>the menu component just like 
  <a href="https://i.stack.imgur.com/n4h3U.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/n4h3U.png" alt="enter image description here"></a></p>
  
  <p>somebody told me I can code like this
  <code>&lt;el-menu style="{backgroundColor: yello}.."</code> but it didn't work</p>