gecko/toolkit/themes/winstripe/global/media/videocontrols.css

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

.controlBar {
    height: 24px;
    background-color: #656363;
}

.playButton {
    background: url(chrome://global/skin/media/pauseButton.png) no-repeat center;
    /* Remove the native button appearance and styling */
    -moz-appearance: none;
    margin: 0px;
    padding: 0px;
    min-height: 24px;
    min-width: 24px;
    border: none;
}
.playButton[paused="true"] {
    background: url(chrome://global/skin/media/playButton.png) no-repeat center;
}

.muteButton {
    background: url(chrome://global/skin/media/muteButton.png) no-repeat center;
    /* Remove the native button appearance and styling */
    -moz-appearance: none;
    margin: 0px;
    padding: 0px;
    min-height: 24px;
    min-width: 24px;
    border: none;
}
.muteButton[muted="true"] {
    background: url(chrome://global/skin/media/unmuteButton.png) no-repeat center;
}