Line with two colors

I have a line chart and I want the line to have two colors, one for historical and one for forecasted data.

I have created a new column to have it added as a legend:

Quarter Color = if(Annual[Quarter]<DATE(2018,4,1),"Inflation","Inflation forecast")

And it works, but the problem is that the line is not continuous anymore and it looks like this:

https://imgur.com/a/5uLrbSl

Any ideas?

Thanks!