Use container helper instead of hard coded container

## What does this MR do?
Add `container_class` helper class to fix layout bug

## What are the relevant issue numbers?
#18333 
## Screenshots (if relevant)
Fixed:    
![Screen_Shot_2016-06-08_at_2.03.38_PM](/uploads/6e7575d711efb8eaf6ba641907b2d607/Screen_Shot_2016-06-08_at_2.03.38_PM.png)
Fluid:     
![Screen_Shot_2016-06-08_at_2.03.56_PM](/uploads/33d3f73781ca9ed129f853abfe9feb4b/Screen_Shot_2016-06-08_at_2.03.56_PM.png)

See merge request !4543