<svg width="200px" height="200px" viewBox="0 0 200 200">
  <!-- axes -->
  <polyline points="100 0, 0 0, 0 100" style="stroke: black; fill: none;"/>

  <!-- normal and rotated square -->
  <rect x="70" y="30" width="20" height="20" style="fill: gray;"/>
  <rect x="70" y="30" width="20" height="20"
    transform="rotate()" style="fill: black;"/>
</svg>