body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    padding-top: 150px;
    box-sizing: border-box;
    background-image:url(fondoooo.JPG);
    background-size: cover;
    background-repeat: no-repeat;
}

header {
    background-color: #333;
    color: #fff;
    text-align: center;
    padding: 15px 0;
    width: 100%;
    left: 0;
    top: 0;
    position: fixed;
}

header h1 {
    margin: 0;
}

section.productos {
    display: flex;
    justify-content: space-around;
    flex-wrap: wrap;
}

article {
    width: 300px;
    margin-bottom: 30px;
    text-align: center;
    background-color: rgba(128, 128, 128, 0.521);
}

article img {
    width: 100%;
    height: auto;
    border: 1px solid #ddd;
    border-radius: 5px;
}

footer {
    background-color: #333333cc;
    color: #fff;
    text-align: center;
    padding: 0.1px 0;
    position: fixed;
    width: 100%;
    bottom: 0;
}