proposed-skeleton.svg

<svg class="lens" width="viewbox[2]" height="viewbox[3]" viewBox="0 0 viewbox[2] viewbox[3]" preserveAspectRatio="none">
  <svg class="aperture" width="viewbox[2]" height="viewbox[3]" viewBox="0 0 viewbox[2] viewbox[3]" preserveAspectRatio="xMinYMid slice">
    <defs>
      <g id="notes"><!-- note shapes are defined here -->
        <rect id="note-1" rx="5" ry="5" height="10" width="10"/>
        <rect id="note-2" rx="5" ry="5" height="10" width="20"/>
        <rect id="note-3" rx="5" ry="5" height="10" width="30"/>
        <rect id="note-4" rx="5" ry="5" height="10" width="40"/>
      </g><!--notes-->
    </defs>

    <svg class="voice0" width="viewbox[2]" height="viewbox[3]" viewBox="viewbox.join(' ')">
      <!-- stamp the note shapes here -->
      <use x="" y="" xlink:href="#note-1" class="note">

    </svg><!--voice0-->
  </svg><!--.aperture-->
</svg><!--.lens-->