piskel/src/templates/popup-preview.html

<div style="display:none">
  <script type="text/template" id="popup-preview-partial">
    <style>
      body,
      .popup-container ,
      .preview-container,
      .background-image-frame-container {
        width : 100%;
        height : 100%;
      }

      body {
        margin: 0;
      }

      .popup-container {
        position: absolute;
        background : #333;
      }

      .preview-container {
        position: relative;
      }

      .background-image-frame-container {
        position: relative;
        background-repeat : no-repeat;
      }

      .canvas-container .canvas-background {
        position: absolute;
        top: 0;
        right: 0;
        bottom: 0;
        left: 0;
      }

      .light-picker-background,
      .light-canvas-background .canvas-background {
        background: url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAMAAABEpIrGAAAABlBMVEXf39////8zI3BgAAAAHklEQVR4AWNghAIGCMDgjwgFCDDSw2M0PSCD0fQAACRcAgF4ciGUAAAAAElFTkSuQmCC') repeat;
      }

      .medium-picker-background,
      .medium-canvas-background .canvas-background {
        background: url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAMAAABEpIrGAAAABlBMVEW6urr///82MBGFAAAAHUlEQVR4AWOAAUYoQOePEAUj3v9oYDQ9gMBoegAAJFwCAbLaTIMAAAAASUVORK5CYII=') repeat;
      }

      .lowcont-medium-picker-background,
      .lowcont-medium-canvas-background .canvas-background {
        background: url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAMAAABEpIrGAAAABlBMVEXV1dXb29tFGkCIAAAAHklEQVR4AWNghAIGCMDgjwgFCDDSw2M0PSCD0fQAACRcAgF4ciGUAAAAAElFTkSuQmCC ') repeat;
      }

      .lowcont-dark-picker-background,
      .lowcont-dark-canvas-background .canvas-background {
        background: url('data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAMAAABEpIrGAAAABlBMVEVMTExVVVUnhsEkAAAAHUlEQVR4AWOAAUYoQOePEAUj3v9oYDQ9gMBoegAAJFwCAbLaTIMAAAAASUVORK5CYII=') repeat;
      }
    </style>
    <div class="popup-container  lowcont-dark-canvas-background ">
      <div class="preview-container  canvas-container">
        <div class="canvas-background"></div>
      </div>
    </div>
  </script>
</div>