body {
  font-family: 'Segoe UI', Tahoma, sans-serif;
  background: #000;
  margin: 0;
  padding: 0;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

.phone-frame {
  width: 375px;
  height: 667px;
  position: relative;
  border-radius: 30px;
  overflow: hidden;
  background: url('background-city.jpg') no-repeat center center;
  background-size: cover;
  box-shadow: 0 0 20px rgba(0, 0, 0, 0.6);
  transition: filter 1s ease;
}

.overlay {
  position: absolute;
  inset: 0;
  background: rgba(0, 0, 0, 0.6);
  opacity: 0;
  transition: opacity 1s ease;
  z-index: 1;
}

.button-container {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  opacity: 0;
  z-index: 2;
  transition: opacity 1s ease;
}

button {
  background: #00e0ff;
  border: none;
  color: white;
  padding: 1rem 2rem;
  border-radius: 40px;
  font-size: 1.1rem;
  cursor: pointer;
  transition: background 0.3s ease;
  box-shadow: 0 4px 12px rgba(0, 224, 255, 0.3);
}