Color before Playback

Hello!
I tried everything, but I can’t find, where I can change the color of the video area, which is seen, before you start the video.
It´s black and I want it green like the rest of my site.
I tried to change every parameter in the css-files, but I can´t find it.

http://ww.wp.xz.cn/plugins/media-element-html5-video-and-audio-player/