<style type="text/css">
body{
  font-family: 'Noto Sans', sans-serif;
}

header, nav, section {
  font-family: 'Noto Sans', sans-serif;
  border: 1px solid blue; padding: 1%; 
  margin-bottom: 1px; color: black;
}
header{
    background: linear-gradient(to bottom, #b3dced 0%, #29b8e5 50%, #bce0ee 100%);
    color: red;
    border-radius: 24px;
}
nav{
    background: linear-gradient(to bottom, #fcfcf9 0%, #f3fc46 100%);
    float: left;
    text-align: center;
    border-radius: 24px;
}
section{
      background: linear-gradient(to bottom, #b3dced 0%, #29b8e5 50%, #bce0ee 100%);
}
nav span{
  margin: 0px 10px 0px 0px;
  text-align: center;
}

#marco {
    background-color: white;
    padding: 10px;
    margin: 10px;
    border: 3px solid black;
    border-radius: 24px;
    width: 650px;
    float: right;
    background: linear-gradient(to right, #f85032 0%, #f16f5c 50%, #f6290c 51%, #f02f17 71%, #e73827 100%);
}

#contenedor {
    display: -webkit-box;
    display: -ms-flexbox;
    display: -webkit-flex;
    display: flex;

    -webkit-flex-wrap: wrap;
    flex-wrap:wrap;
}

.vertical {
  padding:3px;
  border:1px solid black;
  background-color:white;
  width:300px;
  height:200px;
}

.horizontal {
  border:1px solid white;
  background-color:white;
  width:300px;
  height:196px;
}
h1 {
	font-size: 2.4em;
	text-align: center;
}
h2 {
	font-size: 1.4em;
	font-style: italic;	
	text-align: center;
}
h3 {
	font-size: 1.0em;
	text-decoration: underline;	
	text-align: center;
}
</style>