#header {
    position: relative;
    height: 50vh;
    margin-top: 40px;
    background: url("https://picsum.photos/1600/700");
    background-position: center;
    background-size: cover;
    color: white;
}

.header-bg {
    position: absolute;
    display: flex;
    align-items: center;
    width: 100%;
    height: 100%;
    background: rgba(0,0,0,.5);
}

#projekty {
    padding: 5% 0;
    text-align: center;    
}

#projekty h1 {
    margin-bottom: 5%;
}

.projekty-container {
    display: flex;
    justify-content: space-between;
}

.projekty-box {
    position: relative;
    width: 24%;
    padding-bottom: 24%;
    background-color: #001350;
    color: white; 
}

.box-content {
    position: absolute; 
    display: flex;
    flex-direction: column;
    justify-content: center;
    width: 100%;
    height: 100%;
    padding: 3%;    
}

@media only screen and (max-width: 960px) {
    .projekty-container {
        flex-wrap: wrap;                    
    }
    
    .projekty-box {
        width: 49%;
        padding-bottom: 49%;
        margin-bottom: 2%;
    }    
}

@media only screen and (max-width: 480px) {
    .projekty-container {
        flex-wrap: wrap;                    
    }
    
    .projekty-box {
        width: 100%;
        padding-bottom: 100%;
        margin-bottom: 2%;
    }    
}