This is a nested <ul>. The contents are 3 divs: one floated left, one right and one empty with a style of clear: both to cause a new line. With no borders these divs don't respect the clear property.

The selects change the clear and border properties for the names elements.

Additionally the markers for the list seem to be out of place...

• 1: This is left
  1: This is right
• 2: This is left
  2: This is right
  • 2:1: This is left
    2:1: This is right
  • 2:2: This is left
    2:2: This is right