Button Center CSS

Question

Usual CSS centering problem, but it's not working for me because I don't know the final width in pixels.

Each button inside the div that contains the complete navigation no longer centers when there is more than one button.

.nav { margin-top: 167px; width: 1024px; height: 34px; } .nav_button { height: 34px; margin: 0 auto; margin-right: 10px; float: left; }

<div class="nav">
  <div class="nav_button">
    <div class="b_left"></div>
    <div class="b_middle">Home</div>
    <div class="b_right"></div>

  </div>
  <div class="nav_button">
    <div class="b_left"></div>
    <div class="b_middle">Contact Us</div>
    <div class="b_right"></div>

  </div>
</div>