body {background-color: #fff;
    color: #00004d;
    font-family: Helvetica, Verdana, Arial;
    margin: 5px;
}
header {text-align: center;
    padding: 10px;
} 
header a {text-decoration: none;
}
header a:link {color: #00004d;
}
header a:visited {color: #00004d;
}
header a:hover {color: #000099;
}
.nav {border: 1px solid #ccc;
    border-width: 3px;
    list-style: none;
    text-align: center;
    margin-left: 170px;
    margin-right: 170px;
}
.nav li {display: inline;
    padding: 15px;
}
.nav a {display: inline-block;
    padding: 8px;
    font-size: 20px;
    font-weight: bold;
    text-decoration: none;       
}
.gift {font-style: italic;}
.nav a:link {color: #00004d;
}
.nav a:visited {color: #00004d;
}
.nav a:hover {color: #000099;
}
ul li {padding: 10px;
}
h3 {font-size: 20px;
    text-align: center;
}
#home {background-color: #f2f2f2;
    border: 1px solid #006622;
    border-width: 5px;
    margin: 70px;
    padding: 20px;
}
#summary {text-align: center;
    font-size: 18px;
}

#demo {background-color: #f2f2f2;
    border: 1px solid #006622;
    border-width: 5px;
    text-align: left;
    color: #00004d;
    margin: 70px;
    padding: 20px;
}
#comment {color: #006622;
    text-align: center;
}
footer {text-align: center;
    padding-top: 50px;
    padding-bottom: 30px;
}
.center {
  display: block;
  margin-left: auto;
  margin-right: auto;
}
@media (max-width: 768px) {
   .nav {display: contents;}
}