When a teacher is grading an assignment in the new interface (in side by side mode) and uses the rubric pop-out feature, it is useful to also see the feedback box (or vice versa). Currently the popped out object covers up the content in the grading pane. I've proposed code to rectify this (this is what I use in my custom theme, I have not tested the numbers in Boost):

/* Prevents Pop Up Rubric from overlapping Feedback textbox */
.path-mod-assign [data-region="grade-panel"] .fitem.popout {left: 10%; right: 30%;}