[bootStrap]導航條上LOGO居中問題

在Bootstrap v3.3.7 (http://getbootstrap.com)中，在導航條內設置LOGO 

<nav class="navbar navbar-default navbar-fixed-top">
		<div class="container">
	  	<div class="navbar-header">
		    <a class="navbar-brand" href="#" >
		    	<img src="img/logo.png" alt="茶語"/> 
		    </a>
		    <button type="button" class="navbar-toggle" data-toggle="collapse" data-target="#navbar-collapse">
		    	<span class="icon-bar"></span>
		    	<span class="icon-bar"></span>
		    	<span class="icon-bar"></span>
		    </button>
		</div>
		
	    <div class="collapse navbar-collapse" id="navbar-collapse">
		    <ul class="nav navbar-nav navbar-right">
		      <li class="active">
			      <a href="#">
			      	<span class="glyphicon glyphicon-home"></span>主頁
			      </a>
		      </li>
		      <li><a href="#">HTML</a></li>
		      <li><a href="#">CSS</a></li>
		      <li><a href="#">JavaScript</a></li>
		      <li><a href="#">jQuery</a></li>
		      <li><a href="#">BootStrap</a></li>
		      <li><a href="#">工具</a></li>
		      <li><a href="#">問題記錄</a></li>
		    </ul>
		</div>
		</div>
	</nav>

　　結果LOGO沒有居中

更改a的內外邊距樣式能夠解決這個問題

 <a class="navbar-brand" href="#" style="margin: 0 0;padding: 0 0;">
    <img src="img/logo.png" alt="茶語"/> 
</a>