body {
    margin: 0;
    padding: 0;
    font-family: Arial, sans-serif;
}

.header {
    background-color: #333;
    color: white;
    padding: 20px;
    text-align: center;
    font-size: 24px;
    position: sticky;
    top: 0;
    z-index: 100;
}

.content {
    display: flex;
    flex-wrap: wrap;
    gap: 20px;
    padding: 20px;
    justify-content: center;
}

.column {
    flex: 1;
    min-width: 300px;
    display: flex;
    flex-direction: column;
    gap: 20px;
}

.item {
    border-radius: 8px;
    padding: 15px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}