Facebook Like Box Move to Center

Question

I want to center facebook live feeds. I have tried below code.But no luck.

#u_0_0 > ._2p3a {margin: 0 auto !important;}

<script>
  var fb = getElementByClassName("_2p3a");
  fb.style.margin = "0 auto";
</script>

Here is likebox code.

<?php if (Mage::getStoreConfig('a4c_facebook/general/enabled')) : ?>

<fb:like-box 
href="<?php echo Mage::getStoreConfig('a4c_facebook/general/fb_page_url'); ?>" 
width="900px" 
height="<?php echo Mage::getStoreConfig('a4c_facebook/likebox/height'); ?>" 
show_faces="<?php echo (Mage::getStoreConfig('a4c_facebook/likebox/show_faces')) ? 'true' : 'false'; ?>" 
border_color="<?php echo Mage::getStoreConfig('a4c_facebook/likebox/border_color'); ?>" 
stream="<?php echo (Mage::getStoreConfig('a4c_facebook/likebox/stream')) ? 'true' : 'false'; ?>" 
header="<?php echo (Mage::getStoreConfig('a4c_facebook/likebox/header')) ? 'true' : 'false'; ?>"></fb:like-box>

 <?php endif; ?>