About the format with the output of the floating point Numbers for width of two kinds of different s-CodePudding

Manual mentioned in the format "width is a definition of the minimum field width of decimal int
"But if we use float? Also can be tried, but there will be two different cases, 6, 7 lines of code to run with one line of code to run, but in three or four line of the output @ how disappeared,
So what the reasons for this difference is?

 print (" {0:=^ 5} ". The format (' @ ')) # normal 

Print (" {0:=^ 5.0} ". The format (' @ ')) # after floating point Numbers are all 0 
 the condition of thePrint (" {0:=^ 5.00} ". The format (' @ ')) 

Print (" {0:=^ 5.01} ". The format (' @ ')) not all # after floating point Numbers 0 
 the condition of thePrint (" {0:=^ 5.1} ". The format (' @ ')) 
Output: 
==@==
=====
=====
==@==
==@==