Different volume display in multiple instances with same CSS

I’ve customised CSS for a player, and the first (of four) instance on the page displays perfectly, but in the subsequent three instances, the volume bars are all squished together horizontally in all browsers. Pulling my hair out & can’t find the error. Suggestions, please? Thank you!! Site URL: http://bit.ly/Wgi9ei (WP 3.5.1)

http://ww.wp.xz.cn/extend/plugins/wp-miniaudioplayer/