Zebra highlighting for child rows with Bootstrap theme

Currently there is a problem with highlighting if a table have child rows, when using `rowspan` for example:

![childrows-hover](https://cloud.githubusercontent.com/assets/1911270/2600010/84afa1f0-baf3-11e3-9768-0b251acd9fb7.png)

See on the screen-shot the central row is hovered but its child rows (e.g. ALARM_WATER) is unhighlighted.
My solution might look a bit over-complicated but I could not come up with a better one with pure CSS.