Shows how to style <pwa-auth> using shadow parts

styles.css

/* The Sign In button itself */
pwa-auth::part(signInButton) {
  color: white;
  background-color: green;
  transform: rotate3d(0, 0, 1, 10deg);
}

/* The MS button */
pwa-auth::part(microsoftButton) {
  color: teal;
  font-family: "Comic Sans MS"; /*So sorry*/
  text-decoration: underline;
  font-size: 1.2em;
}

/* The Google button */
pwa-auth::part(googleButton) {
  box-shadow: inset 8px 0 1px orange;
  letter-spacing: 4px;
  font-size: 1.2em;
}

/* The Facebook button */
pwa-auth::part(facebookButton) {
  font-family: "Segoe Script", "script";
  font-size: 1.2em;
}

/* The Facebook icon */
pwa-auth::part(facebookIcon) {
  transform: rotateZ(50deg);
}

/* The dropdown menu */
pwa-auth::part(dropdownMenu) {
  border-radius: 10px 0;
  border: 3px dotted blue;
  margin-top: 20px;
}