<!DOCTYPE html>

<html>
<head>
  <style>
    .box {
      display: inline-block;
      height: 120px;
      width: 200px;
      margin: 10px;
      border: 1px solid black;
      background-repeat: no-repeat;
    }

    .linear1 {
      background-image: linear-gradient(to top left, white -20px, 10px, black 120px);
    }

    .linear2 {
      background-image: linear-gradient(to top left, white -20%, blue, 60%, black 120%);
    }

    .linear3 {
      background-image: linear-gradient(0deg, white -20%, 30%, blue, black 120%);
    }

    .linear4 {
      background-image: linear-gradient(to top left, white 20px, 20px, black 120px);
    }

    .linear5 {
      background-image: linear-gradient(to top left, white 0%, 90%, black 90%);
    }

    .linear6 {
      background-image: linear-gradient(0deg, white 50%, 50%, black 50%);
    }
  </style>
  <script>
    if (window.testRunner) {
      var dumpPixels = true;
      testRunner.dumpAsText(dumpPixels);
    }
  </script>
</head>
<body>

  <div class="linear1 box"></div>
  <div class="linear2 box"></div>
  <div class="linear3 box"></div>
  <br>
  <div class="linear4 box"></div>
  <div class="linear5 box"></div>
  <div class="linear6 box"></div>

</body>
</html>