Changing aesthetics in ggplot generated by svars package in R

Question

I'm using the svars package to generate some IRF plots. The plots are rendered using ggplot2, however I need some help with changing some of the aesthetics.

Is there any way I can change the fill and alpha of the shaded confidence bands, as well as the color of the solid line? I know in ggplot2 you can pass fill and alpha arguments to geom_ribbon (and col to geom_line), just unsure of how to do the same within the plot function of this package's source code.

# Load Dataset and packages
library(tidyverse)
library(svars)
data(USA)

# Create SVAR Model
var.model <- vars::VAR(USA, lag.max = 10, ic = "AIC" )
svar.model <- id.chol(var.model)

# Wild Bootstrap

cores <- parallel::detectCores() - 1
boot.svar <- wild.boot(svar.model, n.ahead = 30, nboot = 500, nc = cores)

# Plot the IRFs

plot(boot.svar)

I'm also looking at the command for a historical decomposition plot (see below). Is there any way I could omit the first two facets and plot only the bottom three lines on the same facet?

hist.decomp <- hd(svar.model, series = 1)
plot(hist.decomp)