html, body {
    margin-left: 5%;
    margin-right: 5%;
    padding: 0;
  }
body{
    background: rgba(22, 17, 17, 0.301) ;    
  }
  .contenido{
   background:rgb(243, 187, 4) ;

  }
  h1{
    font-family: 'Times New Roman', serif;  
    color: #ffff;
    text-align: center;
  }
  
  p{
    font-size: 1.2em;
    text-align: justify;
    margin-right: 3%;
    margin-left: 3%;
  }
  
  li{
    font-size: 1.2em;
    text-align: justify;
    margin-right: 3%;
  }
 
  #header{
    width: 100%; 
  }
   
  .cabecera h1{
    background: #343a40 ;
    padding-top: 1%;
    padding-bottom: 1%;
  }
  
  .texto{
    padding-top: 1%;
    padding-left: 2%;
    padding-right: 2%;
    padding-bottom: 1%;
    color: midnightblue;
  }
  
  .ejemplo{
    background: gainsboro;
    border-style:inset;
    font-size: 1.2em;
    font-family: Calibri, sans-serif;
    text-align: justify;
    color:midnightblue ;
  }
  
  footer{
    font-family: 'Times New Roman', serif;  
    font-size: 1.5em;
    width: 100%; 
    background: #495057;
    color: #e6bd0a;
    margin-top: 3%;
    padding-top: 3%;
    padding-bottom: 3%;
    text-align: center;
  }