I was sitting in my office in the library looking up some trivia about X-Files, of all things, lol. It was about 4:15pm EST and nobody else was in the staff area of the floor my office is located on, the lower level. I know this because when the last person other than me leaves, they always turn off the overhead fluorescent lights in the shared workspace outside of my office. As I'm browsing websites, I see something to my right, directly in the doorway of my office. I see it out of the corner of my eye. It's a pair of legs wearing wide-leg pants, kinda like those linen pants or gaucho pants you see people wear. It was belted and it looked like it had some sort of pattern to it. It startled me and I looked up only to see nobody was there. Interestingly, the library here on campus has a history of strange sightings and occurrences and there have even been some strange things happen on my floor of the library, like the lights in two of the study rooms going on and off by themselves.