/* Placeholder image for header background */
.header-bg {
    width: 100%;
    height: 300px;
    background-color: #3498db;
    background-image: linear-gradient(45deg, #3498db, #2c3e50);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 24px;
    text-align: center;
}

/* Placeholder image for Leipzig Zoo */
.leipzig-zoo-img {
    width: 100%;
    height: 300px;
    background-color: #27ae60;
    background-image: linear-gradient(45deg, #27ae60, #2ecc71);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 24px;
    text-align: center;
    border-radius: 8px;
}

/* Placeholder image for Berlin Zoo */
.berlin-zoo-img {
    width: 100%;
    height: 300px;
    background-color: #e74c3c;
    background-image: linear-gradient(45deg, #e74c3c, #c0392b);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 24px;
    text-align: center;
    border-radius: 8px;
}

/* Placeholder image for Transportation */
.transport-img {
    width: 100%;
    height: 300px;
    background-color: #f39c12;
    background-image: linear-gradient(45deg, #f39c12, #d35400);
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    font-size: 24px;
    text-align: center;
    border-radius: 8px;
}