css3實現信紙/同窗錄效果

實現思路：
網格背景，由css3的線性漸變來實現。
紙上的打孔，由圓和圓柱組成，多個打孔，能夠由box-shadow的平鋪來實現。

實際代碼：

<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>