Hello,
You should be able to activate it on Day View in one of two ways.
Your first option is to use body.tribe-events-day instead of just body.events-day.
Alternatively, you can just remove the body.{classname} qualifier here, so that any instance of .tribe-events-list-event-description will be hidden, e.g.:
.tribe-events-list-event-description {
display: none !important;
}
Play around with these options and see what you find. For further customization tweaks, I’d highly recommend getting and learning to use a free tool like Firebug if you use FireFox, or the Developer Tools for either Safari or Chrome. These make customizing HTML and CSS much easier, so definitely look into them.
Cheers,
George