html, body {
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 0;
}

#canvas-wrapper {
  width: 800px;
  height: 400px;
  position: relative;
}

canvas {
  position: absolute;
  top: 0;
  left: 0;
}

#maze {
  border: 1px solid black;
  background: black;
}

html, body {
  width: 100%;
  height: 100%;
  margin: 0;
  padding: 0;
}

body {
  background: antiquewhite;
}

#canvas-wrapper {
  width: 800px;
  height: 400px;
  position: relative;
  top: 10%;
  margin: 0 auto;
}

canvas {
  position: absolute;
  top: 0;
  left: 0;
}

#maze {
  border: 2px solid black;
  background: black;
}

Put the canvas horizontally centered
Put the canvas horizontally centered

Change the background color, add some vertical offset to the canvas and
change the canvas border to 2px.
