layout 
flex

nn hhhhhhhhhhh
nn mmmmmmmmmmm
nn mmmmmmmmmmm
nn mmmmmmmmmmm
nn mmmmmmmmmmm
nn fffffffffff

n nav
h header
m main/inhalt
f footer

n fix links, immer gesamte höhe
h immer gesamte breite bis auf nav fixe höhe
f immer gesamte breite bis auf nav fixe höhe
m horizontal und vertikal center

row
    element 1   
        nav
    elemen1 2
        column
            header
            main       
            footer
        /column      
/row

<div class="container">
  <nav class="nav left">left</nav>
  <section class="main">
    <div class="col header">header</div>
    <div class="col middle">
      <div class="ver_hor_center">
        main
      </div>
    </div>
    <div class="col footer">footer</div>
  </section> 
</div>


.container {
  display: flex;
  flex-flow: row;
  min-height: 50px;
  
}
.left {
  flex: 0 0;
  background-color: blue;
  height: 100vh;
}
.main {
  width: 100%;
  background-color: red;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  height: 100vh;
 }
.col {
  margin: 2px;
}
.header {
    flex: 0 0;
    height: 20px;
    background: yellow;
  }
.middle {
    height: 100%;
    background: pink;
  }
.footer {
    flex: 0 0;
    height: 20px;
    background: cyan;
  }

.ver_hor_center
{
  /* horizontal und vertikal zentrieren */
  position: absolute;
  top: 25%;
  left: 25%;
}
