body {
    background-color: lightgray;
    font-family: Arial, Helvetica, sans-serif;
}

#container {
    width: 1100px;
    margin: 0px auto;
    border: 4px solid gray;
}
header {
    background-color: red;
    height: 100px;
    width: 100%;
    margin: 0px;
    text-align: center;
    line-height: 100px;
    color: antiquewhite;
    border-bottom: 2px solid black;
}
nav ul li {
  float: left;
  list-style: none;
  margin: 20px;
  line-height: 10px;
}
/*Quitar Subrayado*/
a {text-decoration: none;}
ul {text-align: center; display: inline-block;}

#content{
  float:left;
  width: calc(80%  - 20px);
    background-color: green;
    min-height: 500px;
    padding: 10px
}

.article{
  color: white;
  margin-top: 15px;
  margin-bottom: 15px;
  border-bottom: 1px solid white;
  padding-bottom: 20px
}
  
aside{
    float: left;
    width: calc(20% - 20px);
    background-color: coral;
    min-height: 500px;
    padding: 10px;
}


footer{
    background-color: black;
    color: white;
    text-align: center;
    height: 30px;
    line-height: 30px;
}


.clearfix{
    clear:both;
}

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