<style>
dummy{background-color:red;}
article, aside, details, figcaption, figure,
footer, header, hgroup, menu, nav, section {
    display: block;
}
body {
    //background-image: url("bilder/MV-Sonne.jpg");
}
nav {
    background-color:red;
}
div#Content {
  display: -webkit-flex;
  display: flex;
  -webkit-flex-direction: row; /* Standard */
  flex-direction: row; /* Standard */
}
header#Banner {
    //background-color:lightgreen;
    background-image: url("../bilder/MV-Sonne.jpg");
    background-repeat: no-repeat;
    background-position: top center;
    height:300px;
     color:darkred;
    text-align:center;
     padding:5px; 
}
aside {
    line-height:30px;
    background-color:#eeeeee;
     /*height:300px;
    width:100px;
    float:left;   */
    -webkit-flex-basis: 10%;
    flex-basis: 10%;
    min-width: 100px;
     padding:5px; 
}
 section {
    width:1150;
    float:left;
     padding:10px; 
}
footer {
     background-color:black;
    color:white;
    clear:both;
     text-align:center;
     padding:5px; 
}
</style>