.iu-container {
  max-width: 480px;
  margin: 30px auto;
  text-align: center;
  padding: 20px;
  border-radius: 12px;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
  background: #fff;
}
#iu-files { margin: 10px 0; }
#iu-convert {
  background: #0073aa;
  color: white;
  border: none;
  padding: 10px 20px;
  cursor: pointer;
  border-radius: 8px;
}
#iu-progress-container {
  width: 100%;
  height: 20px;
  background: #eee;
  border-radius: 10px;
  margin-top: 15px;
}
#iu-progress-bar {
  height: 100%;
  width: 0%;
  background: #4caf50;
  border-radius: 10px;
  text-align: center;
  color: #fff;
  font-size: 12px;
}
#iu-download a {
  display: block;
  margin-top: 10px;
  color: #0073aa;
  text-decoration: none;
}