.cml-flag-tiny-cs:before {
    content: url(https://theseuslab.cz/wp-content/uploads/ceceppaml/flags/tiny/cs_CZ.png);
    width: 16px;
    height: 11px;
    display: inline-block;
    vertical-align: middle;
    margin-right: 5px;
}
.cml-flag-small-cs:before {
    content: url(https://theseuslab.cz/wp-content/uploads/ceceppaml/flags/small/cs_CZ.png);
    width: 32px;
    height: 33px;
    display: inline-block;
    vertical-align: middle;
    margin-right: 5px;
}