css3实现信纸/同学录效果的示例代码

<div class="bg-grid"></div><style>.bg-grid {    height: 400px;    padding: 10px;    padding-top: 64px;    background-color: #efefef;    background-image:   linear-gradient(#e7e6e6 1px, transparent 0),                        linear-gradient(90deg, #e7e6e6 1px, transparent 0);    background-size: 21px 21px, 21px 21px;    background-position: center;}.bg-grid:before,.bg-grid:after{    content: '';    position: absolute;    z-index: 0;    left: 50%;    transform: translateX(-50%);    display: inline-block;    background-color: #fff;    height: 28px;    box-shadow: 68px 0 0 0 #fff,                 calc(68px * 2) 0 0 0 #fff,                 calc(68px * 3) 0 0 0 #fff,                 calc(68px * 4) 0 0 0 #fff,                 calc(68px * 5) 0 0 0 #fff,                 -68px 0 0 0 #fff,                 calc(68px * -2) 0 0 0 #fff,                 calc(68px * -3) 0 0 0 #fff,                 calc(68px * -4) 0 0 0 #fff,                 calc(68px * -5) 0 0 0 #fff;}.bg-grid:before {    top: 0;    width: 10px;}.bg-grid:after {    top: 26px;    width: 28px;    border-radius: 50%;}.bg-grid{}</style>