.block_fbcomments .fb-comments, 
.block_fbcomments .fb-comments span,
.block_fbcomments .fb-comments iframe[style] {width: 100% !important;}

.block_fbcomments .fb-like, 
.block_fbcomments .fb-like span, 
.block_fbcomments .fb-like iframe[style] {width: 100% !important;}