Life steal from weapon damage

I have a small doubt concerning life steal. I know the life steal from geat affect damage caused with weapon. But in the case of fire strike, cadence, etc where damage come from weapon and some flat bonus; is the life steal based on the total damage or only the weapon damage part?
Example: fire strike at lvl 1 do 100%weapon damage+4 fire. So life steal is from the 100% or 100%+4 damage??

Attachment: img1.jpg
Attachment: Before hit.jpg
Attachment: after hit.jpg

If it’s right in the skill, a part of it, it heals form the full damage the skill does. If you have global, only WD is taken into account.

You leech from full skill damage, including flat.

To answer this question, i decided to make a test with a cheated character:
-The character have the starting weapon, to have a low physical weapon damage.
-Used fire strike tree maxed, to have a lot of fire, and chaos damage.
-Maxed Hungering void to reduce my life enought to have a good difference to see how much life i leech.
-Used devotions with life leech.
-Low physique, but lot of cunning and spirit, to have good damage bonus, but low life regen.
-Reduced my constitution to 0 to not interfere with the life regen.

Here you can see the stats, average damage, life leech, and the dummy life leech res :

Here is the life before any hit (11345 hp):

Here is after hit (12962 hp , 7466 + 304 +285 dmg):

Now we will calculate the life leeched:

-7466 main dmg
-285 + 304 secondary dmg
-26% life leech
-25% dummy life leech res
(7466+285+304)0,26(1-0,25)= 1570 life leeched

Difference before and after hit: 12962-11345 = 1617

As we can see, calculated life leeched with fire strike and the difference in life are close. The difference of 47 hp come from 25,7 life regen, due to time to attack, and print screen.
The damage can’t be only from weapon damage, as we can see the base weapon is betwen 722 - 1372 dmg ( even with 122% bonus from firestrike and 56% bonus physical wont deal all that.).
With this, we have a proof default weapon attack skills benefit from life leech on the total damage.