Plot timeseries and regression line for two groups of data - r

Question

I have data from two sites across years (note the differences in sampling years). A sample is below:
df<- data.frame( year= c(seq(1997,2016,1), seq(2001,2017,1)),
site= c(rep("cr", 20),rep("ec", 17)),
mean= sample(1:50,37))
I would like to make a time series-like graph of mean for each year. Each data point would be connected (in the typical zig-zag fashion of time-series graphs) and then a regression line is superimposed to indicate the trend. I have created a time series-like plot using ggplot (I do not mind a solution from base package), but I am having trouble superimposing a dashed-regression line for each site without error.
Here is the code I have tried:
f1 <- ggplot(data = df, aes(x = year, y = mean, group= site, color=
site))+
geom_line(aes(color=site)) +
geom_point( aes(color=site),size=0.5)+
geom_smooth(method = "lm", se = FALSE, size= 0.5, aes(fill=site,
linetype= 2 ))+
scale_linetype_manual(values=c("solid", "solid"))+
scale_color_manual(values=c("#CC0000", "#000000"))+
theme_minimal()+
scale_x_continuous("Year",limits = c(1997, 2020), breaks =
seq(1995,2020,5)) +
scale_y_continuous("Mean Monthly Abundance", limits = c(0, 1500),
breaks=seq(0, 1500, by = 100)) +
theme_bw()+
theme(axis.line = element_line(colour = "black"),
panel.grid.major = element_blank(),
panel.grid.minor = element_blank(),
panel.background = element_blank())
f1
A few details I would like this graph to illustrate:
Each group (site) will have a different color (black ,red) for the points and the line connecting each point
The regression lines for each group (site) will be dashed and match the color specified above.
The regression lines should NOT extend to the y-axis and be limited to the length the of the data
-Points do not need to be visible. Only the line connecting each point should be visible.
Preferably the dashed regression line will NOT display the shaded 95% CI.

Answer 1

As #kath stated, adding linetype = "dashed" would fix it. I've made some minor modifications to the code as well:
ggplot(data = df, aes(x = year, y = mean, group= site, color = site))+
geom_line() +
geom_point(size=0.5)+
geom_smooth(method = "lm", se = FALSE, size= 0.5, linetype = "dashed")+
scale_color_manual(values=c("#CC0000", "#000000"))+
theme_minimal()+
scale_x_continuous("Year",limits = c(1997, 2020), breaks =
seq(1995,2020,5)) +
scale_y_continuous("Mean Monthly Abundance", limits = c(0, 1500),
breaks=seq(0, 1500, by = 100)) +
theme_bw()+
theme(axis.line = element_line(colour = "black"),
panel.grid.major = element_blank(),
panel.grid.minor = element_blank(),
panel.background = element_blank())