.titulo{
    background: grey;
    color: white;
    text-align: center;
    padding: 14px;
    font-size: 40px;
    border-radius: 30px;
}

.principal{
 background-image:url("https://i.pinimg.com/736x/c3/bf/b7/c3bfb7e05ab74d66f4aeb7fc1e055d04.jpg");
 text-align: center;
    font-family:sans-serif;
    
}
 
.contenedor{
  
margin:auto;  
background: grey;
padding: 30px;
border-radius: 30px;
border: 5px red solid;
width: 400px;
display:inline-flex;

}

a{
outline: none;
    text-decoration: none;
    display: inline-block;
    width: 19.5%;
    margin-right: 0.625%;
    text-align: center;
    line-height: 3;
    color: black;
}
li:last-child a{
  margin-right: 0;   
}
a:link, a:visited, a:focus{
background: yellow;  
   
    margin: 5px;
}
 a:hover{
  background: red;   
}
 a: active{
  background:red;
     color: white;
}