/*灰色网格背景*/
.bg_gray_grid{
    background: white;
    background-image: linear-gradient(#eeeeee 2px, transparent 0),
    linear-gradient(90deg, #eeeeee 2px, transparent 0),
    linear-gradient(#eeeeee 1px, transparent 0),
    linear-gradient(90deg, #eeeeee 1px, transparent 0);
    background-size: 50px 50px, 50px 50px,
    10px 10px, 10px 10px;
}