How to fill grids?

How to fill light blue above the dotted line and slightly darker colour below dotted line in whole figure.

Answer 1

[VBBV]

clear
clc
x = 0:30;
y = ones(1,length(x))*202
ylim(([0 1600]))
plot(x,y,'b--','linewidth',4)
xx = [0 30 30 0];
yy = [0 0 200 200];
xx2 = [0 30 30 0];
yy2 = [203 203 1600 1600];
patch(xx,yy,'blue','EdgeColor','none','FaceAlpha',0.5);
hold on
patch(xx2,yy2,'red','EdgeColor','none','FaceAlpha',0.5);

Try with different coordinates and colors

[VBBV]

Refer patch for filling