.obdelnik1 {
    width: 20%;
    background-color: aqua;
    padding: 2%;
    float: left;
}

.obdelnik2{
    width: 20%;
    background-color: chocolate;
    float: left;
    padding: 2%;
}

.obdelnik3{
    width: 20%;
    background-color: red;
    padding: 2%;
    float: left;
}

.obdelnik4{
    width: 20%;
    background-color: blueviolet;
    padding: 2%;
    float: left;
}

@media screen and (max-width:900px){
    .obdelnik1 {
        width: 100%;
        background-color: rgba(0, 255, 255, 0.336);
        padding: 5%;
        float: left;
        text-align: center;

    }

    .obdelnik2{
        width: 100%;
        background-color: rgba(210, 105, 30, 0.363);
        float: left;
        padding: 5%;
        text-align: center;
    }

    .obdelnik3{
        width: 100%;
        background-color: rgba(255, 0, 0, 0.281);
        padding: 5%;
        float: left;
        text-align: center;
    }

    .obdelnik4{
        width: 100%;
        background-color: rgba(128, 0, 128, 0.37);
        padding: 5%;
        float: left;
        text-align: center;
    }
    
}