CSS rollover buttons

I am trying to make a rollover menu that swaps different backgrounds and changes the color of the text.

My first approach has the button looking the way I want it to with the correct image and text centered, but does not work for the rollover.

input.button      {
      background-image:url('images/stonelblu.png');
      background-position:center;
      background-repeat:no-repeat;
      border:none;
      width:150px;
      height:42px;
      color:white;
      font-family:"Baskerville Old Face";
      font-size:20px;
      
}

input.button:hover      {
      background-image:url('images/stoneblk.png');
      color:olive;
}


My second approach has the rollover working, but I cannot get the text to align vertically.  It wants to have the text nested at the top of the button.

p.navbuttons a {
      background-image:url('images/stonelblu.png');
      background-position:center;
      border:none;
      width:150px;
      height:42px;
      color:white;
      font-family:"Baskerville Old Face";      vertical-align:middle;
      text-align:center;
      font-size:20px;
}

p.navbuttons a:hover, p.navbuttons a:active {
      background-image:url('images/stoneblk.png');
      background-position:center;
      border:none;
      width:150px;
      height:42px;
      color:olive;
      font-family:"Baskerville Old Face";
      text-align:center;
}

I have tried the "vertical-align" and a couple others but it doesn't seem to really do any good.  I have tried to give it a negative value to make it go below where it puts it, but it doesn't move.  However if I put a positive number it will raise it to the point it is off or partially off the button.