Decrease background color opacity on schedule page

[coder13]

Is your feature request related to a problem? Please describe.

Room colors are hard. It's hard to get text to render well, and normally when we pick bright sharp colors, they just look bad on the page.

Describe the solution you'd like

Decrease background color opacity for scheduled events.

Much like I've done in competition groups. I would recommend setting the alpha channel to a value like 7f.