* { 
    margin: 0; 
    padding: 0; 
    box-sizing: border-box; 
} 
  
body { 
    height: 100vh; 
    width: 100vw; 
} 
  
.background { 
    height: 100vh; 
    width: 100vw; 
    background-color: skyblue; 
} 
  
.bird { 
    height: 100px; 
    width: 160px; 
    position: fixed; 
    top: 40vh; 
    left: 30vw; 
    z-index: 100; 
} 
  
.pipe_sprite { 
    position: fixed; 
    top: 40vh; 
    left: 100vw; 
    height: 70vh; 
    width: 6vw; 
    background-color: green; 
} 
  
.message { 
    position: fixed; 
    z-index: 10; 
    height: 10vh; 
    font-size: 10vh; 
    font-weight: 100; 
    color: black; 
    top: 12vh; 
    left: 20vw; 
    text-align: center; 
} 
  
.score { 
    position: fixed; 
    z-index: 10; 
    height: 10vh; 
    font-size: 10vh; 
    font-weight: 100; 
    color: goldenrod; 
    top: 0; 
    left: 0; 
} 
  
.score_val { 
    color: gold; 
}