background-image: linear-gradient(0deg, transparent calc(100% - 1px), #f0f0f0 calc(100% - 1px)),
linear-gradient(90deg, transparent calc(100% - 1px), #f0f0f0 calc(100% - 1px));
background-size: 16px 16px;
background-repeat: repeat;
background-position: center center;【コピペOK】CSSで方眼紙のような模様の背景を実装する方法
