body {
    background-color: gray;
    background-image: url("images/bg.jpg");
    background-size: cover;
  }
  
  /*中略*/
  
  header {
    padding: 40px;
    height: 80px;
    background-image: url("images/pattern.png");
    background-repeat: repeat;
  }
  
  /*中略*/
  
  footer {
    padding: 40px;
    height: 40px;
    background-color : black;
    color: white;
    background-image: url("images/logo.png");
    background-repeat: no-repeat;
    background-size: 200px 50px;
    background-position: center bottom;
  }