body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(120deg, #667eea, #764ba2);
  margin: 0;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #222;
}

.upload-box {
  background: #fff;
  padding: 2rem;
  border-radius: 16px;
  box-shadow: 0 12px 40px rgba(40,60,180,0.2);
  width: 320px;
  text-align: center;
}

.upload-box h1 {
  margin-bottom: 1.5rem;
  font-weight: 700;
  color: #3a3a8a;
}

.upload-box input[type="file"] {
  margin: 1rem 0;
  font-weight: 600;
}

.upload-box button {
  background-color: #667eea;
  color: white;
  border: none;
  border-radius: 10px;
  padding: 0.7rem 2rem;
  font-weight: 700;
  cursor: pointer;
  transition: background-color 0.3s ease;
  font-size: 1rem;
  width: 100%;
}

.upload-box button:hover {
  background-color: #5064c5;
}

.message {
  margin-top: 1rem;
  font-weight: 600;
  font-size: 1rem;
  min-height: 24px;
  color: #d63649; /* error red */
}

.message.success {
  color: #2f9e44; /* green */
}