Originally from CSS Ninja, I've adapted it to use text for the treee markers, use svg images and show an open folder.

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    1. File 1
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    1. File 1
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    1. File 1
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      6. Subfile 6
    1. File 1
      1. Subfile 1
      2. Subfile 2
      3. Subfile 3
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      5. Subfile 5
      6. Subfile 6