html - Get an element of navbar to center -

i have navbar below. how center element help video.

  .header_title{        font-size: 20px;        color: white;    }      .center {        text-align:center;    }        .center {        float:none;        display:inline-block;        *display:inline; /* ie7 fix */        *zoom:1; /* haslayout ie7 trigger */        vertical-align: top;      }

<div class="navbar navbar-default navbar-fixed-top navbar_form" role="navigation">        <div class="navbar-header">          <button type="button" class="navbar-toggle" data-toggle="collapse" data-target=".navbar-collapse">            <span class="sr-only">toggle navigation</span>          </button>          <a class="navbar-brand" href="/"><font class="header_title" >some text</font></a>        </div>                     <!-- fixed navbar want center this.-->           <div class="navbar-collapse collapse center">            <a class="navbar-brand" href="#"><font class="header_title" >help video</font></a>            </div>      </div><!--/.nav-collapse -->          

but not coming center. doing wrong?

remove below styles stylesheet.

.center { float:none; display:inline-block; *display:inline; /* ie7 fix */ *zoom:1; /* haslayout ie7 trigger */ vertical-align: top; }