Enhancement: CSS styling to group the Graphs with the device on the left

[rchac]

[trendal]

This came from me. In troubleshooting a blank graph issue, it suddenly dawned on me that the devices on the left were related to the graphs on the main area. I had been missing that connection. At a minimum a horizontal divider line between the devices would help that out a lot. I don't personally like a full wrap around line, it gets kinda busy so still thinking about what might be the best visual cue.