re-implement background color for construction alert content
re-implement background color for construction alert content

(refs #16214)

jessecarterMOOSE/moose,idaholab/moose,milljm/moose,SudiptaBiswas/moose,lindsayad/moose,milljm/moose,harterj/moose,lindsayad/moose,laagesen/moose,idaholab/moose,nuclear-wizard/moose,sapitts/moose,andrsd/moose,nuclear-wizard/moose,andrsd/moose,andrsd/moose,andrsd/moose,bwspenc/moose,nuclear-wizard/moose,sapitts/moose,idaholab/moose,milljm/moose,dschwen/moose,dschwen/moose,idaholab/moose,andrsd/moose,milljm/moose,sapitts/moose,dschwen/moose,SudiptaBiswas/moose,dschwen/moose,SudiptaBiswas/moose,lindsayad/moose,bwspenc/moose,jessecarterMOOSE/moose,jessecarterMOOSE/moose,dschwen/moose,laagesen/moose,nuclear-wizard/moose,harterj/moose,bwspenc/moose,idaholab/moose,jessecarterMOOSE/moose,laagesen/moose,lindsayad/moose,bwspenc/moose,sapitts/moose,bwspenc/moose,sapitts/moose,harterj/moose,harterj/moose,laagesen/moose,laagesen/moose,milljm/moose,harterj/moose,jessecarterMOOSE/moose,SudiptaBiswas/moose,lindsayad/moose,SudiptaBiswas/moose