chromium/chrome/browser/resources/lens/overlay/object_layer.html

<style>
  .object {
    pointer-events: all;
    position: absolute;
  }

  :host([debug-mode]) .object {
    border: 2px solid green;
    opacity: 50%;
  }

  #highlightImgContainer {
    display: none;
  }

  #objectSelectionCanvas {
    top: 0;
    left: 0;
    position: absolute;
    pointer-events: none;
  }
</style>
<canvas id="objectSelectionCanvas" height="[[canvasPhysicalHeight]]"
  width="[[canvasPhysicalWidth]]"
  style$="height: [[canvasHeight]]px; width: [[canvasWidth]]px;"></canvas>
<template id="objectsContainer" is="dom-repeat" items="[[renderedObjects]]">
  <div style$="[[getObjectStyle(item)]]" class="object"
    on-pointerenter="handlePointerEnter" on-pointerleave="handlePointerLeave">
  </div>
</template>
<!-- Provides image source for canvas; element is not displayed. -->
<div id="highlightImgContainer">
  <canvas id="highlightImgCanvas">
</div>