<div class="graph-paper"></div>

:root {
  --bg-color: #fff;
  --line-color-1: #366;
  --line-color-2: #a9a9a9;
}

*, *::before, *::after {
  -webkit-box-sizing: border-box;
  -moz-box-sizing: border-box;
  box-sizing: border-box;
}

body {
  width: 100vw;
  height: 100vh;
  overflow: hidden;
  margin: 0;
  padding: 0;
}

.graph-paper {
  width: 100%;
  height: 100%;
  background-color: var(--bg-color);
  background-image: linear-gradient(var(--line-color-1) 1.5px, transparent 1.5px), linear-gradient(90deg, var(--line-color-1) 1.5px, transparent 1.5px), linear-gradient(var(--line-color-2) 1px, transparent 1px), linear-gradient(90deg, var(--line-color-2) 1px, transparent 1px);
  background-position: -1.5px -1.5px, -1.5px -1.5px, -1px -1px, -1px -1px;
  background-size: 100px 100px, 100px 100px, 20px 20px, 20px 20px;
}