using Statistics
using CairoMakie
f = Figure()
Axis(f[1, 1])
n, m = 100, 101
t = range(0, 1, length=m)
X = cumsum(randn(n, m), dims = 2)
X = X .- X[:, 1]
μ = vec(mean(X, dims=1)) # mean
σ = vec(std(X, dims=1)) # stddev
band!(t, μ + σ, μ - σ, color = :teal) # plot stddev band
lines!(t, μ, color = :tan1,linewidth=5) # plot mean line
f