body{/*ギザギザ背景*/
background-color:antiquewhite;/*背景色*/
background-size:20px 20px;
background-image:
linear-gradient(-135deg,#fff 25%,transparent 0),
linear-gradient(135deg,#fff 25%,transparent 0),
linear-gradient(-45deg,#fff 25%,transparent 0),
linear-gradient(45deg,#fff 25%,transparent 0);
background-position:10px 0px,10px 0px,0px 0px,0px 0px;
}