header {
      text-align: center;
      background: url('../img/background.png');
      background-size: cover;
      color: rgb(255, 255, 255);
    }
    a {
      color: white;
    }
    h1 {
      font-size: 70px;
    }
    img {
margin: 40px 0px 0px 0px;
border: 7px;
border-radius: 20px;
visibility: hidden;
}
    ul {
padding: 10px;
background: rgba(11, 1, 1, 0.5);
}
    li {
      display: inline;
      padding: 0px 10px 0px 10px;
    }
    article {
      max-width: 500px;
      padding: 20px;
      margin: 0 auto;
    }
    
    @media (max-width: 500px) {
      h1 {
        font-size: 36px;
        padding: 5px;
      }
      li {
        padding: 5px;
        display: block;
      }
    }