body {
  font-family: Arial, sans-serif;
  margin: 0;
}

header {
  background-color: #333;
  color: #fff;
  padding: 20px;
  text-align: center;
}

header h1 {
  margin: 0;
}

nav {
  background-color: #f1f1f1;
  overflow: hidden;
}

nav ul {
  list-style-type: none;
  margin: 0;
  padding: 0;
  overflow: hidden;
  background-color: #f1f1f1;
}

nav li {
  float: left;
}

nav a {
  display: block;
  color: black;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

nav a:hover {
  background-color: #ddd;
  color: black;
}

#main-content {
  padding: 20px;
}

#main-content article {
  margin-bottom: 20px;a
}

#main-content article img {
  max-width: 100%;
}

aside {
  float: right;
  width: 25%;
  padding: 20px;
  background-color: #f1f1f1;
}

footer {
  background-color: #333;
  color: #fff;
  text-align: center;
  padding: 20px;
}

#message-container {
  display: none;
}