Etch-a-Sketch Advanced: How do I stop lighting up <div>s outside the graph?

Hey there, so I’m on the bonus portions of the Etch-a-Sketch assignment, namely getting all my pixels to light up in random colors.

I didn’t have this problem initially because I set my mouseover to activate a class of colors. But in order to get random colors, I had to tell the mouseover to light up with a “style.setProperty” statement, and that was called on all <div>s including the ones outside the graph.

I tried to setAttribute(“class”) to the divs inside the graph, but then my graph disappears altogether. Can anyone help me understand what I’m doing wrong?