.wrapper {
  display: flex;  
  flex-flow: row wrap;
  font-weight: bold;
  text-align: center;
  font-size: 3.5vw;
}

.wrapper > * {
  padding: 10px;
  flex: 1 100%;
}

.header {
  background: tomato;
}

.footer {
  background: lightgreen;
}

.main {
  text-align: left;
  background: deepskyblue;
}

.aside-1 {
  background: gold;
}

.aside-2 {
  background: hotpink;
}

.button{
  margin-left: auto;
  padding: 8px 16px;
  border: none;
  background: #333;
  color: #f2f2f2;
  text-transform: uppercase;
  letter-spacing: .09em;
  border-radius: 2px;
  font-size: 2vw;
}

@media all and (min-width: 600px) {
  .aside { flex: 1 auto; }
}

@media all and (min-width: 800px) {
  .main    { flex: 3 0px; }
  .aside-1 { order: 1; } 
  .main    { order: 2; }
  .aside-2 { order: 3; }
  .footer  { order: 4; }
}

body {
  padding: 2em; 
}

.navigation {
  list-style: none;
  margin: 0;
  background: deepskyblue;
  display: -webkit-box;
  display: -moz-box;
  display: -ms-flexbox;
  display: -webkit-flex;
  display: flex;
  -webkit-flex-flow: row wrap;
  justify-content: flex-end;
}

.navigation a {
  text-decoration: none;
  display: block;
  padding: 1em;
  color: white;
}

.navigation a:hover {
  background: #00b7f5;
}

@media all and (max-width: 800px) {
  .navigation {
    justify-content: space-around;
  }
}
@media all and (max-width: 600px) {
  .navigation {
    -webkit-flex-flow: column wrap;
    flex-flow: column wrap;
    padding: 0;
  }

  .navigation a {
    text-align: center;
    padding: 10px;
    border-top: 1px solid rgba(255, 255, 255, 0.3);
    border-bottom: 1px solid rgba(0, 0, 0, 0.1);
  }

  .navigation li:last-of-type a {
    border-bottom: none;
  }
}