Background color for cell id.

plot_transmission_timeline.py

     host.plot(transmission_df["goodput_rolling"], "-", color="blue", label="goodput")
     host.set_xlabel("datetime")
     host.set_ylabel("goodput [Mbps]")
+    host.set_ylim([0, 500])
 
     # additional y axes
     par11 = host.twinx()