body {
  font-family: Arial, sans-serif;
  background-color: #f6f7fb;
  margin: 0;
  padding: 0;
  color: #333;
}
header {
  background-color: #283e4a;
  color: white;
  padding: 1em;
  text-align: center;
}
nav a {
  color: white;
  margin: 0 10px;
  text-decoration: none;
}
main {
  padding: 2em;
  max-width: 700px;
  margin: auto;
  background: white;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
}
form {
  margin-top: 20px;
}
form input, form select, form textarea {
  margin: 10px 0;
  padding: 10px;
  font-size: 1em;
  width: 100%;
  max-width: 100%;
  box-sizing: border-box;
}
button {
  padding: 10px 20px;
  background-color: #283e4a;
  color: white;
  border: none;
  cursor: pointer;
}
button:hover {
  background-color: #3b5666;
}
#thumbnail {
  margin-top: 10px;
}