editor-style.css

@import url( 'style.css' );

body#tinymce.wp-editor,
body.wp-autoresize  {
	font-family: 'source-sans-pro-1','source-sans-pro-2', 'Helvetica Neue', Helvetica, Arial, sans-serif !important;
	padding:  10px !important;
	background: #fff !important;
}

body#tinymce.layout-1c.wp-editor,
body.layout-1c.wp-autoresize {
	max-width: 760px !important;
	background: #fff !important;
}