Make all positive value bar graph the same color theme as bar graph with negative values in ggplot

I just started playing with ggplot yesterday. My code for the bar graph with negative values work as I have expected:

dtf1 <- data.frame(ID = c(1:10),Diff = c(-5:4))dtf1$colour <- ifelse(dtf1$Diff < 0, "firebrick1","steelblue")dtf1$hjust <- ifelse(dtf1$Diff > 0, 1.3, -0.3)ggplot(dtf1,aes(ID,Diff,label="",hjust=hjust))+  geom_text(aes(y=0,colour=colour))+  geom_bar(stat="identity",position="identity",aes(fill = colour))

But not so when I apply the same code to a different dataset that has only positive values

dtf <- data.frame(ID = c(1:10),Diff = rnorm(10,3))dtf$colour <- ifelse(dtf$Diff < 0, "firebrick1","steelblue")dtf$hjust <- ifelse(dtf$Diff > 0, 1.3, -0.3)ggplot(dtf,aes(ID,Diff,label="",hjust=hjust))+  geom_text(aes(y=0,colour=colour))+  geom_bar(stat="identity",position="identity",aes(fill = colour))

I find that I can tweak the last line of the code to get blue colors for my positive bars,geom_bar(stat="identity",position="identity",fill="steelblue")

My two questions therefore are:

1. However, the color isn't as expected:

It seems like the color may be closer to turquoise3 instead of to steelblue.

2. Moreover, I am also interested in finding why the same code wouldallow the positive bars to have different colors.

I must have been asking a very simple question. I don't know how best to phrase it and therefore have difficulty finding the solution. I apologize if the question has already been asked and I would be glad to delete myself.