Pure CSS collapsible tree menu | The CSS Ninja

Example from the [CSS] Ninja

Folder 1
1. File 1
2. Subfolder 1
  1. Filey 1
  2. Subfolder 1
    1. File 1
    2. Subfolder 1
      1. Subfile 1
      2. Subfile 2
      3. Subfile 3
      4. Subfile 4
      5. Subfile 5
      6. Subfile 6
  3. File 3
  4. File 4
  5. File 5
  6. File 6
Folder 2
1. File 1
2. Subfolder 1
  1. Subfile 1
  2. Subfile 2
  3. Subfile 3
  4. Subfile 4
  5. Subfile 5
  6. Subfile 6
Folder 3
1. File 1
2. Subfolder 1
  1. Subfile 1
  2. Subfile 2
  3. Subfile 3
  4. Subfile 4
  5. Subfile 5
  6. Subfile 6
Folder 4
1. File 1
2. Subfolder 1
  1. Subfile 1
  2. Subfile 2
  3. Subfile 3
  4. Subfile 4
  5. Subfile 5
  6. Subfile 6
Folder 5
1. File 1
2. Subfolder 1
  1. Subfile 1
  2. Subfile 2
  3. Subfile 3
  4. Subfile 4
  5. Subfile 5
  6. Subfile 6