I usually solve this using x padding-left and -x text-indent. Thus, the text that is wrapped will be indented, but not the first line.
#navigation li { padding-left: 10px; text-indent: -10px; }
If you want to change the height of the line, however, note that you will need some kind of margin from the previous elements, otherwise they just compress together. May be:
#navigation li a { line-height: 1.2em; } #navigation li+li a { margin-top: 10px; }
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