.ymaps-layers-pane {
    filter: grayscale(1);
    -ms-filter: grayscale(1);
    -webkit-filter: grayscale(1);
    -moz-filter: grayscale(1);
    -o-filter: grayscale(1);
}
[class*="ymaps-2"][class*="-ground-pane"] {
    filter: url("data:image/svg+xml;utf8,<svg xmlns=\'http://www.w3.org/2000/svg\'><filter id=\'grayscale\'><feColorMatrix type=\'matrix\' values=\'0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0.3333 0.3333 0.3333 0 0 0 0 0 1 0\'/></filter></svg>#grayscale");
    /* Firefox 3.5+ */
    -webkit-filter: grayscale(100%);
    /* Chrome 19+ & Safari 6+ */
}