body {
    font-family: sans-serif;
    text-align: center;
    margin: 0;
    padding: 0;
    background: #f4f4f4;
}
h2 {
    margin: 20px 0;
}
.gallery {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 10px;
    padding: 10px;
    max-width: 1000px;
    margin: auto;
}
.item img {
    width: 100%;
    height: auto;
    border-radius: 8px;
    cursor: pointer;
    transition: transform 0.2s;
}
.item img:hover {
    transform: scale(1.05);
}

/* Popup style */
#popup {
    position: fixed;
    display: none;
    top: 0; left: 0;
    width: 100%; height: 100%;
    background-color: rgba(0,0,0,0.8);
    justify-content: center;
    align-items: center;
    z-index: 999;
}
#popup img {
    max-width: 90%;
    max-height: 90%;
    border: 5px solid #fff;
    border-radius: 10px;
}
.upload-form {
    margin: 20px auto;
    display: flex;
    flex-direction: column;
    gap: 10px;
    max-width: 300px;
    align-items: center;
}
.upload-form input[type="file"] {
    padding: 5px;
}
.upload-form button {
    padding: 8px 16px;
    background: #28a745;
    color: white;
    border: none;
    border-radius: 5px;
    cursor: pointer;
}
.upload-form button:hover {
    background: #218838;
}

@media screen and (max-width: 600px) {
    .gallery {
        grid-template-columns: repeat(auto-fit, minmax(100px, 1fr));
    }
    #popup img {
        max-width: 95%;
        max-height: 80%;
    }
}