body {
    background-color: yellow;
    font-family: Arial, Helvetica, sans-serif;
    margin: 0;
    padding: 0;
}


header {
    text-align: center;
    background-color: white;
    padding: 20px;
    box-shadow: 0px 0px 10px gray;
}

header h1 {
    color: darkblue;
    margin-bottom: 5px;
}


nav {
    background-color: #f2f2f2;
    padding: 10px 0;
    text-align: center;
}

nav ul {
    list-style-type: none;
    padding: 0;
    margin: 0;
}

nav li {
    display: inline;
    margin: 0 15px;
}

nav a {
    text-decoration: none;
    color: darkblue;
    font-weight: bold;
}

nav a:hover {
    color: darkred;
}


main {
    width: 80%;
    min-width: 700px;
    max-width: 1100px;
    margin: 20px auto;
    background-color: white;
    padding: 20px;
    box-shadow: 0px 0px 10px gray;
}


section h2 {
    color: darkred;
    border-bottom: 2px solid lightgray;
    padding-bottom: 5px;
    margin-top: 20px;
}


article {
    margin-bottom: 15px;
}


img {
    display: block;
    margin: 20px auto;
    border: 5px solid lightgray;
}


aside {
    background-color: #e6f2ff;
    padding: 10px;
    margin-top: 20px;
}


footer {
    text-align: center;
    padding: 10px;
    margin-top: 20px;
    background-color: lightgray;
    font-size: 14px;
}