body {
    font-family: Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: #f4f4f4;
}

header {
    background: #35424a;
    color: #ffffff;
    padding: 20px 0;
    text-align: center;
}

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

nav ul li {
    display: inline;
    margin: 0 10px;
}

nav a {
    color: white;
    text-decoration: none;
}

main {
    padding: 20px;
}

#profile, #messages, #posts {
    background: white;
    padding: 20px;
    border-radius: 5px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

#postInput, #messageInput {
    width: 100%;
    height: 60px;
}

button {
    margin-top: 10px;
}