html, body{
    height: 100%;
    margin:0;
}

body{
    display: flex;
    justify-content: center;
    align-items: center;
}

.container{ 
    display: flex;
    flex-wrap: wrap;
    width: 400px;
    height: 400px;
    border: 4px solid black;
}

.kvadratik{
    width: 50px;
    height: 50px;
    background-color: rgb(253, 253, 221);
}

.black{
    background-color: black; 
}