Here's a template that does stuff

product-demo.liquid

<div class="commit-create  position-relative ">
      <div class="">
        <textarea class="form-control file-editor-textarea js-blob-contents js-code-textarea " rows="17" name="gist[contents][][value]" data-filename="product-demo.liquid" data-codemirror-mode="" data-allow-unchanged="true" data-hotkey-scope-id="code-editor" data-codemirror-fixed-height="true" placeholder="Enter file contents here" aria-label="Enter file contents here" spellcheck="false" style="display: none;"></textarea>
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        <label class="text-normal drag-and-drop hx_drag-and-drop position-relative d-flex flex-justify-between" hidden="">
    <input accept=".gif,.jpeg,.jpg,.mov,.mp4,.png,.svg,.csv,.docx,.fodg,.fodp,.fods,.fodt,.gz,.log,.md,.odf,.odg,.odp,.ods,.odt,.pdf,.pptx,.txt,.xls,.xlsx,.zip" type="file" multiple="" class="manual-file-chooser manual-file-chooser-transparent top-0 right-0 bottom-0 left-0 width-full ml-0 form-control rounded-top-0" id="blob-dragged-file-input">
    <span class="color-bg-subtle position-absolute top-0 left-0 rounded-bottom-2 width-full height-full" style="pointer-events: none;"></span>
    <span class="position-relative pr-2" style="pointer-events: none;">
      <span class="default">
        Attach files by selecting or pasting them.
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      <span class="loading">
        <svg style="box-sizing: content-box; color: var(--color-icon-primary);" width="16" height="16" viewBox="0 0 16 16" fill="none" data-view-component="true" class="v-align-text-bottom mr-1 anim-rotate">
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</svg>
          <span class="js-file-upload-loading-text" data-file-upload-message="Uploading your files…">
            Uploading your files…
          </span>
      </span>
      <span class="error bad-file">
        We don’t support that file type.
        <span class="drag-and-drop-error-info">
          <span class="btn-link">Try again</span> with a
          GIF, JPEG, JPG, MOV, MP4, PNG, SVG, CSV, DOCX, FODG, FODP, FODS, FODT, GZ, LOG, MD, ODF, ODG, ODP, ODS, ODT, PDF, PPTX, TXT, XLS, XLSX or ZIP.
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      </span>
      <span class="error bad-permissions">
        Attaching documents requires write permission to this repository.
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          <span class="btn-link">Try again</span> with a GIF, JPEG, JPG, MOV, MP4, PNG, SVG, CSV, DOCX, FODG, FODP, FODS, FODT, GZ, LOG, MD, ODF, ODG, ODP, ODS, ODT, PDF, PPTX, TXT, XLS, XLSX or ZIP.
        </span>
      </span>
      <span class="error repository-required">
        We don’t support that file type.
        <span class="drag-and-drop-error-info">
          <span class="btn-link">Try again</span> with a GIF, JPEG, JPG, MOV, MP4, PNG, SVG, CSV, DOCX, FODG, FODP, FODS, FODT, GZ, LOG, MD, ODF, ODG, ODP, ODS, ODT, PDF, PPTX, TXT, XLS, XLSX or ZIP.
        </span>
      </span>
      <span class="error too-big js-upload-too-big">
      </span>
      <span class="error empty">
        This file is empty.
        <span class="drag-and-drop-error-info">
          <span class="btn-link">Try again</span> with a file that’s not empty.
        </span>
      </span>
      <span class="error hidden-file">
        This file is hidden.
        <span class="drag-and-drop-error-info">
          <span class="btn-link">Try again</span> with another file.
        </span>
      </span>
      <span class="error failed-request">
        Something went really wrong, and we can’t process that file.
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        </span>
      </span>
    </span>
    <a class="Link--muted position-relative d-inline" href="https://docs.github.com/github/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax" target="_blank" data-ga-click="Markdown Toolbar, click, help" id="dd_blob-dragged-file-input_md_link" aria-labelledby="tooltip-1646797899084-3002">
      <svg aria-hidden="true" height="16" viewBox="0 0 16 16" version="1.1" width="16" data-view-component="true" class="octicon octicon-markdown v-align-bottom">
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</svg>
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    <primer-tooltip for="dd_blob-dragged-file-input_md_link" data-type="label" data-direction="nw" hidden="" id="tooltip-1646797899084-3002" class="hx_tooltip" role="tooltip">Styling with Markdown is supported</primer-tooltip>
  </label>

    </div>