* {
  margin: 0px;
  padding: 0px;
}

body {
  font-family: Gotham, "Helvetica Neue", Helvetica, Arial, sans-serif;
}

.caja {
  width: 95%;
  max-width: 1200px;
  margin: 2px auto;
  padding: 2px;
}

header {
  margin-bottom: 20px;
}

h1 {
  font-size: 1.4em;
  margin-bottom: 15px;
}

section {
    margin: 10px 0;
}

h2{
    font-size: 1.1em;
    margin-bottom: 10px;
}

h3{
    font-size: 0.9em;
    margin-bottom: 10px;
}
 p{
     text-align: justify;
     line-height: 15pt;
     margin: 2px 0;
 }

 #problema{
     margin: 10px 0px;
 }
 #ejemplo{
    padding-left: 75px;
 }