Source/WebCore/css/fullscreen.css

:-webkit-full-screen {
    background-color: white;
}

:root:full-screen-document:not(:full-screen) {
    overflow:hidden;
}

video:-webkit-full-screen {
    background-color: black !important;
    position: static !important;
    margin: 0 !important;
    height: 100% !important;
    width: 100% !important;
    -webkit-box-flex: 1 !important;
    display: block !important;
}

img:-webkit-full-screen {
    width: auto;   
    height: 100%;
    max-width: 100%;
}

video:-webkit-full-page-media:-webkit-full-screen::-webkit-media-controls-panel {
    bottom: 0px;
}