associations – AssociationMap with formatting

Build an Association using AssociationMap, where the keys are the letters of the Alphabet() and the values are the same letters with the following Style:

  1. The size of the letter should be set to twice that of the letter’s position in the English alphabet.
  2. The Background of the nth letter in the Alphabet should be set to the nth color from the “ColorList” in the “Legacy” color scheme.(Hint:Use LetterNumber and ColorData).

While trying to solve the above problem (courtesy Wolfram U team), I could just do the plain AssociaionMap.

Input:

AssociationMap (f,{Alphabet()}) 

Output:

<{a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z}->f({a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z})> 

Clueless about positioning (1) and setting background (2) in the needed format.