<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <title>vue-flat-surface-shader</title>
    <link rel="stylesheet" href="https://fonts.cat.net/css?family=Teko:400,500">
    <style>
      html, body {
        margin: 0;
        padding: 0;
      }
      #app {
        position: relative;
      }
      .shader {
        width: 100%;
        height: 100vh;
      }
      .mask {
        width: 100%;
        height: 100vh;
        position: absolute;
        background-color: rgba(0, 0, 0