If I understand correctly, do you want to float divs left and right inside your div shell, but keeping the full shell div full height on the screen?
If so, the right and left divs, of course, go into the shell, and you use {... float: left; position: relative;} and {... float: right; position: relative;} to swim on their sides.
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<div style="clear: both;"></div> - div (, span) CSS {... clear: both;}
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