Fix x-axis labels clipped on graph page

[bracyw]

Observed Behavior

On initial load of the graph page, the graph plot area is tall enough that the x-axis number labels sit below the fold. The user has to scroll down to see them.

Expected Behavior

The graph should be slightly shorter on load so the x-axis labels are visible without scrolling.

Steps to Reproduce

1. Open the graph page
2. Add any topic to plot
3. Without scrolling, note that the x-axis numbers are not in view