Better explained and lighter section conflict warning

[MinhxNguyen7]

CONCLUSION:

• Lighter shade of gray.
• Tooltip should appear when hovering anywhere in the row but not conflict with current buttons/tooltips.

Original RFC: I strongly think that the graying out of sections that conflict should be lighter and better-explained.

The former is because I think it currently implies that that section can't be added for some reason/leads to an error condition, which isn't the case. Additionally, that implicitly contradicts the flow where someone adds a bunch of classes to their schedule.

The latter would alleviate the issue above as well as not telling the user that they're necessarily doing something wrong. I think a small tooltip under all of the buttons with explanatory text about why it's grayed out would be very helpful.