Graph style on hover

Working on a few ideas for our graph style. I put the labels on the y-axis inside so the left edge is cleaner, and on hover the vertical line appears with the time stamp in the bottom, and a target-like circle on the value at that point.

There aren't any labels on the y-axis because these are live graphs of the last 75 seconds of activity. People might miss the labels though so I'll text this and also a graph with "30 sec ago" etc. on the y-axis.