Drag Courses

[LeoLee5566]

As we discussed in our last meeting, one may want to drag courses to make one's own collection. I'm working on it.

[LeoLee5566]

see https://codepen.io/leolee5566-the-vuer/pen/mdOVYwX?editors=0011, also push to a new branch for download

[LeoLee5566]

I cannot find information about MATH263 on the website (we don't have this course this year either), thus nothing to show when the mouse hovers on it. Maybe we should also delete it on Layoutcourses.