Figure 4.20. Columns that are 15em wide inside a 45em container with the default column-gap valueChangingcolumn-gapto 0 ,however,givesusourfullthree-columnlayoutasshown
inFigure4.21.Withoutacolumn-gap,there’snowsufficientroomforthreecolumns.
Aswithcolumn-width,thevalueofcolumn-gapshouldbeeither 0 orapositive
lengthvalue.Negativelengthssuchas-2emareinvalid.
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