h1, h2, h3, .nejakaTrida {
    background-color: aqua;
    color: beige;
}

h3.nejakaTrida {
    width: 50em;
}
.pozadi {
    background-color: aquamarine;
}
.text {
    color: #ff9cf3;
}

.trojsloupcova .sloupec p {

}