What composes the mass of an electron?

A definition of mass, as found in Google:
"Mass is a measurement of the amount of matter or substance in an
object.
It's the total amount of protons, neutrons, and electrons in an object."
It's "accepted" since the 60s that protons and neutrons are not
elementary particles anymore. As stated in the Standard Model of
Elementary Particles, protons and neutrons are composed of quarks, with
different flavors.
https://www.quantumdiaries.org/wp-content/uploads/2014/03/2000px-Standard_Model_of_Elementary_Particles.svg_.jpg
But electrons are thought as elementary particles, so they can't be
formed by a collection of other elementary particles. Even quarks are
currently thought as working together with elementary gluons (QCD, Gauge
Bossons).
So, what is THE MATTER that electrons contain?
This is one of many FAILS of the current SMEP.
Is that the electron's mass is composed of unknown matter? Maybe of
electromagnetic nature?
After all, modern civilization is based on what electrons can do, isn't
it?
THEY KNOW NOTHING, AS IN RELATIVISM!.