* {
    box-sizing: border-box;
  }
  
  body {
    margin: 0;
  }
  #bg {
    position: fixed; 
    top: 0; 
    left: 0; 
    
    /* Preserve aspet ratio */
    min-width: 100%;
    min-height: 100%;
  }

  /* Style the header */
  .header {
    background-position: center;
    padding: 20px;
    padding-top: 200px;    
    text-align: center;
    background-image: url(https://www.asociacionvirgendelasnieves.org.ar/Portada_recorte_2.png)
  }
  
  /* Style the top navigation bar */
  .topnav {
    overflow: hidden;
    background-color: #333;
  }
  
  /* Style the topnav links */
  .topnav a {
   /* float: left;*/
    display: block;
    color: #f2f2f2;
    text-align: center;
    padding: 14px 16px;
    text-decoration: none;
  }
  
  /* Change color on hover */
  .topnav a:hover {
    background-color: #ddd;
    color: black;
  }