Modificar el CSS del Uploader Media WordPress +3.5

Uploader Media Wordpress

	.media-menu,.attachments-browser,.media-frame-menu,#wp\_editimgbtn,.media-router .active:after {
        display:none;
    }
	.media-modal{
		width:600px;
		max-height:400px;
		margin:auto;
	}
	.media-frame-title h1{
		font-family:"gill sans";
	}
	.media-frame-title,.media-frame-router,.media-frame-toolbar{
		left:0px;
		text-align:center;
	}
	.media-frame-content,.uploader-inline-content{
		margin-top:40px;
		position:static;
		text-align:center;
	}
	.media-toolbar,.media-toolbar-primary{
		position:static;
		width:128px;
		padding:0px;
		margin:auto;
		float:none;
		text-align:center;
	}
	media-button-insert{
		display:block;
	}
	.media-router{
		float:none;
		width:100px;
		margin:auto;
	}
	.media-router a{
		border-right:0px;
	}

Fuente: Customize Media Manager https://wordpress.org/support/topic/customize-media-manager?replies=5