body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #e0f7fa, #80deea);
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.container {
  background: #fff;
  padding: 30px;
  border-radius: 12px;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.1);
  text-align: center;
  max-width: 500px;
  width: 100%;
}

h1 {
  color: #115ca8;
  margin-bottom: 10px;
}

.description {
  font-size: 14px;
  color: #555;
  margin-bottom: 20px;
}

.file-input {
  margin-bottom: 15px;
}

.btn {
  background: #115ca8;
  color: #fff;
  border: none;
  padding: 10px 20px;
  border-radius: 6px;
  cursor: pointer;
  font-size: 16px;
}

.btn:hover {
  background: #0d4882;
}

#loading-overlay {
  position: fixed;
  top: 0;
  left: 0;
  right: 0; 
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  display: none;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  color: #fff;
  font-size: 18px;
  z-index: 9999;
}

.loader {
  border: 6px solid #f3f3f3;
  border-top: 6px solid #115ca8;
  border-radius: 50%;
  width: 50px;
  height: 50px;
  animation: spin 1s linear infinite;
  margin-bottom: 10px;
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}