Как сделать градиент css

.img { 
  display: block; 
  width: 300px; 
  height: 200px; 
  background-image: linear-gradient(to bottom, black 0%, transparent 100%), url(https://i.stack.imgur.com/Cbwec.jpg); 
  background-size: cover; 
  background-position: center; 
}

<div class="img"></div>