How to Handle Split Data in `Charts`?

I have a dataset I want to have split between past/historic data and future/predicted data. The values for the predicted data take the last value from pastData and apply a decay function to show how much of something is left.

I have the data split into two arrays (sampleData_History and sampleData_Future); I have also attempted this with the data combined (sampleData) and tried a conditional in the .foregroundStyle property.

Chart {
			ForEach(sampleData_History) { item in
				RuleMark(x: .value("Now", Date.now, unit: .hour)).foregroundStyle(.orange)

				LineMark(
					x: .value("time", item.date, unit: .hour),
					y: .value("mg", item.amount)
				)
				.foregroundStyle(Color.blue)
				AreaMark(
					x: .value("time", item.date, unit: .hour),
					y: .value("mg", item.amount)
				).foregroundStyle(Color.teal.opacity(0.2))
			}
			ForEach(sampleData_Future) { item in
				LineMark(
					x: .value("time", item.date, unit: .hour),
					y: .value("mg", item.amount)
				)
				.foregroundStyle(Color.red)
				AreaMark(
					x: .value("time", item.date, unit: .hour),
					y: .value("mg", item.amount)
				).foregroundStyle(Color.red.opacity(0.2))
			}
		}

The above code yields the screenshot below. In the ideal case, I'd like to have everything AFTER the RuleMark line be a different color. Am I missing something? Where might I look to figure this out?

EDIT: I have also tried separating them into series to no avail