Blue
Haku's hair looks to be a charcoal black colour .
The bay bridge is a kind of gray/green.
red
Red.
reddish orangish or rusty color
The traditional (and original) color of the bridge was black. Now, for some reason, it is an ugly shade of blue.
Red
The bridge that replace the 17th century bridge in 1924-1925 is called the Eitai-bashi or Eitai Bridge. The modern bridge is a blue illuminated bridge. See Sources and related links for a photo.
Believe it or not, the color doesn't stand for anything. The people of San Francisco, who paid for building the bridge, liked the color especially against the sunset. The color is called "International Orange". See the link below.
because of its color
Red
because of color blindness