* {
  margin: 0px;
  padding: 0px;
}
body {
    background-color: lightgray;
    front-family: Arial, Helvetica, sans-serif;
}

#container {
    width: 1100px;
    margin: 0px auto;
    border: 4px solid gray;
}
/*Segundo Paso*: Configurar Encabezado */
header {
background-color: red;
height: 100px;
width: 100%;
margin: 0px;
text-align: center;
line-height: 100px;
color: antiquewhite;
border-bottom: 2px solid black;
}
/*Tercer Paso: Crear Menu*/
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;}