List the column names of multiple data frames as one data frame

How would I capture the column names of multiple data frames (all having differing number of columns) into one data frame; so that i can quickly see what columns each data frame has and which ones may be common to all.

I've got a small example below but it does not get me exactly what I'm after. shorter columns repeat to match the length of the longer columns. (If I use a list how can view each data frame's column names side-by-side)?

dfA <- data.frame(colA = runif(10), colB=LETTERS[1:10])
dfB <- data.frame(col1 = rnorm(5), col2=LETTERS[11:15], col3 = LETTERS[20:24], colB=LETTERS[14:18])
listDF <- list(dfA=names(dfA), dfB=names(dfB))