Why Minimum Packet Size is 64B?

[Iluvnetwork]

L4(Assuming TCP) Header + L3 Header + L2 Header + CRC = 20 + 20 + 18 = 58 byte. Where are the rest of 6 byte coming from?

I know that anything under 64 byte frame would be a runt. I am guessing that since runts are the fragments of packet collisions, they would get dropped if switches are fragment-free or store and forwarding. Otherwise, they would get dropped at the end device after checking the FCS. Please let me know if my guesses are wrong. 

Lastly, I believe that late collision can only be detected by store-and-forwarding switch or by checking FCS. Please let me know if I am wrong.

[Rolf Fischer · Accepted solution]

Have a look at the excellent explanations here: https://supportforums.cisco.com/t5/lan-switching-and-routing/slot-time-and-minimum-ethenet-fame-size/td-p/2797341

[Iluvnetwork]

I think Peter is Network God. His explanations always impress and enlighten me :)
Just curious are all engineers at Cisco smart like Peter?