.bookbg{
	background:linear-gradient(90deg, #addbeb, #69badd);
}
/*color*/
    .book__model::before{
      background:linear-gradient(180deg, #112f4c, #082139);
    }

    .cover{
      background: linear-gradient(135deg, rgba(255,255,255,.06), rgba(0,0,0,.12)),
                  linear-gradient(180deg, #112f4c, #0a3053);
    }

    .spine{
      background:
        linear-gradient(60deg, rgba(255,255,255,.26), rgba(255,255,255,0) 28%),
        linear-gradient(180deg, #105ca2, #235380);
    }
/*書間距*/
    .shelf{
      gap: 160px; 
      transform-style:preserve-3d;
      padding-right: 160px;
    }