/* 背景画像の設定 */
.wood-background {
  background-image: linear-gradient(rgba(0, 0, 0, 0.3) 0%, rgba(0, 0, 0, 0.8) 100%), url("images/background.jpg");
  background-size: cover;
  background-position: center;
  background-repeat: no-repeat;
  background-attachment: fixed;
}