Q:

Change color of outline in multicolored grouped barplot

This is a barplot I have:

How can I have a black outline for each bar and also, change the font size of the axis label and values on the label?
mm1=melt(data[,c('label','cut_scorer1','cut_scorer2')], id = 1)
assign(cut_score,ggplot(mm1, aes(x = label, y = value, width = 0.8)) + 
    geom_bar(aes(fill = variable), stat = "identity", position = "dodge")+ sale_fill_manual(values=alpha(c('light green','dark green'),0.7), name = "Scorer", 
    labels = c("1", "2")) + 
    labs(title = paste(subject_name,"Cutting", sep = " - "), x = "", y = 
    "Score") + 
    theme(text = element_text(size = 15)) + coord_cartesian( ylim = 
    c(min(mm1$value),max(mm1$value))))

A:

I really recommend taking a look at the documentation for geom_bar() (as well as the basic ggplot2 documentation), but this might help get you started.
You can add an outline to your bars by using colour = "black", and you can change the axis labels by using labs(). We use the arguments within theme() to change the font size on your axis labels and tickmarks. See the code below:
# example dataframe
df <- data.frame(time = factor(c("Lunch","Dinner"), levels=c("Lunch","Dinner")),
                 total_bill = c(14.89, 17.23))

plot <- ggplot(data = df, aes(x = time, y = total_bill, fill = time)) +
        geom_bar(colour = "black", stat = "identity") +
        labs(x = "Meal", y = "Total Bill") +
        theme(axis.title.x = element_text(size = 13, face = "bold"),
              axis.title.y = element_text(size = 13, face = "bold"),
              axis.text.x = element_text(size = 12),
              axis.text.y = element_text(size = 12))
print(plot)

