[Python] find a button by cssselector

html 如下：

<div class="admin-welcome-hero">
       <h1>Welcome to the Meeting System</h1>
       <div class="admin-intro">
          Click on a current or previous meeting to edit or review details, or create a new meeting.
       </div>
       <button class="btn btn-lg new-meeting" ng-click="vm.newmeeting(this);"> 
         Create a new meeting 
       </button> 
</div>

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The css selector you are looking for is:

By.CssSelector("button.new-meeting")

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if you want to be more specific you can do

By.CssSelector("div.admin-welcome-hero button.new-meeting")