These thin yellow lines indicate the good side of the yellow brick road. (It's technically a yellow brick half-plane.) The thicker line demarcates 7 days of safety buffer. (If you keep your safety buffer at 7 days or higher then you're immune to being stung. If anything comes up, just flatten your yellow brick road. It will take effect after the 7-day akrasia horizon but since you have that much safety buffer, you're golden!)