body{/*ギンガムチェック(茶色)の背景*/
background-size:20px 20px;
background-color:#ffe;
background-image:
linear-gradient(90deg, rgba(100,50,0,0.3) 50%, transparent 50%),
linear-gradient(rgba(100,50,0,0.3) 50%, transparent 50%);
}