.container {
  position: relative;
  margin: 20px auto;
  padding: 20px;
  border-radius: 16px;
  font-family: 'Poppins', sans-serif;
  text-align: center;
  max-width: 900px;
  background: #121212; /* Ultra-dark background */
  color: #e0e0e0; /* Soft white text for readability */
  box-shadow: 0 12px 35px rgba(0, 0, 0, 0.3);
  z-index: 1;
}

/* Dark gradient border (deep blue + teal green) */
.container::before {
  content: '';
  position: absolute;
  top: -4px;
  left: -4px;
  right: -4px;
  bottom: -4px;
  z-index: -1;
  border-radius: 20px;
  background: linear-gradient(135deg, #003366, #005544); /* Dark blue to dark green */
}

.container h1 {
  font-size: 40px;
  font-weight: 800;
  color: #222;
  background: linear-gradient(90deg, #0d6efd, #20c997);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  text-align: center;
  margin-bottom: 30px;
  letter-spacing: 1.5px;
  text-shadow: 1px 1px 3px rgba(0,0,0,0.1);
  padding: 10px 0;
  border-bottom: 3px solid #0d6efd;
  display: inline-block;
}

.drop-zone {
  border: 2px dashed #4f46e5;
  padding: 30px;
  border-radius: 12px;
  cursor: pointer;
  margin-bottom: 20px;
  transition: background 0.3s;
  color: #4f46e5;
}

.drop-zone.dragover {
  background: #eef2ff;
}

.file-list {
  margin-bottom: 20px;
  text-align: left;
}

.file-item {
  padding: 8px;
  background: #f9fafb;
  margin: 5px 0;
  border-radius: 8px;
  font-size: 14px;
}

.second-button {
  padding: 12px 25px;
  background-color: #007bff;
  color: #fff;
  border: none;
  border-radius: 8px;
  font-size: 18px;
  cursor: pointer;
  transition: all 0.3s ease-in-out;
  margin-bottom: 16px;
}

.second-button:hover {
  background-color: #0056b3;
  box-shadow: 0 8px 18px rgba(0, 0, 0, 0.2);
  transform: translateY(-2px);
}

.clear-btn {
  background: #e11d48;
}

.clear-btn:hover {
  background: #be123c;
}

.progress {
  margin-top: 15px;
  font-size: 14px;
  color: #16a34a;
}

#download-btn {
  display: none;
  margin-top: 10px;
}