I have several buttons that have variable width and I would like them to all be a certain width. When I attempted to add width: 150px; it doesn't work.  How do I create these buttons that will all have a set width? 
Here is a Fiddle and here is the code:
HTML
<p><a class="dark_button 150px-width" href="#">Lorem</a></p>
<p><a class="dark_button 150px-width" href="#">Lorum Ipsum</a></p>
<p><a class="dark_button 150px-width" href="#">Lorum Ipsum dolor</a></p>
<p><a class="dark_button 150px-width" href="#">Lorum Ipsum dolor sit amet</a></p>
CSS
.dark_button{
  border-top: 1px solid #969696;
  background: #000000;
  background: -webkit-gradient(linear, left top, left bottom, from(#545454), to(#000000));
  background: -webkit-linear-gradient(top, #545454, #000000);
  background: -moz-linear-gradient(top, #545454, #000000);
  background: -ms-linear-gradient(top, #545454, #000000);
  background: -o-linear-gradient(top, #545454, #000000);
  padding: 5px 10px;
  -webkit-border-radius: 8px;
  -moz-border-radius: 8px;
  border-radius: 8px;
  -webkit-box-shadow: rgba(0,0,0,1) 0 1px 0;
  -moz-box-shadow: rgba(0,0,0,1) 0 1px 0;
  box-shadow: rgba(0,0,0,1) 0 1px 0;
  text-shadow: rgba(0,0,0,.4) 0 1px 0;
  color: #e3e3e3 !important;
  font-size: 14px;
  text-decoration: none;
  vertical-align: middle;
}
.dark_button:hover {
  border-top-color: #4f4f4f;
  background: #4f4f4f;
  color: #ccc;
  text-decoration:none;
}
.dark_button:active {
  border-top-color: #4a4a4a;
  background: #4a4a4a;
}
.150px-width{
 width: 150px;
}
 
     
     
     
     
     
    