* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  background: #f0f2f5;
  min-height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
}

.container {
  width: 90%;
  max-width: 600px;
  padding: 2rem;
}

h1 {
  text-align: center;
  color: #1a73e8;
  margin-bottom: 2rem;
}

.converter-box {
  background: white;
  border-radius: 10px;
  padding: 2rem;
  box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.drop-zone {
  border: 2px dashed #1a73e8;
  border-radius: 8px;
  padding: 2rem;
  text-align: center;
  transition: all 0.3s ease;
  cursor: pointer;
  margin-bottom: 1.5rem;
}

.drop-zone.dragover {
  background: #e8f0fe;
  border-color: #1557b0;
}

.drop-zone-content {
  color: #5f6368;
}

.upload-icon {
  width: 64px;
  height: 64px;
  margin-bottom: 1rem;
  opacity: 0.7;
}

.small {
  font-size: 0.9rem;
  color: #80868b;
  margin-top: 0.5rem;
}

.convert-btn {
  width: 100%;
  padding: 1rem;
  background: #1a73e8;
  color: white;
  border: none;
  border-radius: 5px;
  font-size: 1rem;
  cursor: pointer;
  transition: background 0.3s ease;
}

.convert-btn:hover {
  background: #1557b0;
}

.convert-btn:disabled {
  background: #80868b;
  cursor: not-allowed;
}

.error {
  border-color: #dc3545;
  animation: shake 0.5s;
}

@keyframes shake {
  0%,
  100% {
    transform: translateX(0);
  }
  25% {
    transform: translateX(-10px);
  }
  75% {
    transform: translateX(10px);
  }
}