header {
    position: fixed;
    top: 0px;
    width: 100%;
    height: 19px;
    padding: 25px 0px;
  }
    
    @media only screen and (max-width: 600px) {
    body {
      background-color: lightblue;
    }
  }
  
  .container {
    display: flex; /* or inline-flex */
  }
  
  #navbar {
      background: red;
      position: fixed;
      top: 0px;
      width: 100%;
  }