* {
  margin: 0;
  padding: 0;
}

body {
  font: 16px Georgia, serif;
}

ul {
  list-style-type: none;
}

#container {
  margin: 2% auto;
  color: blue;
}

#container > .main {
  border: 1px solid #999;
  padding: 1%; 
  margin-bottom: 1px;
  color: black;
}

header, nav, section {
  background: #eee;
}

section #titulo {
  text-align: center;
}

article {
  border-bottom: 1px solid #000;
  padding-top: 5px;
}

img #imagen {
  display: block; 
  margin: auto;
  width: 90%;
  max-height: 410px;
  padding: 5%;
}

footer {
  background: #eee;
  text-align: center;
}

nav span {
  margin: 0px 10px 0px 0px;
}

h3 span.ok {
  color: green;  

}

h3 span.error {
  color: red;  
  
}