dark.css

:root {
  --background-color: rgb(40, 44, 53);
  --text-color: rgb(240, 240, 240);
}

.icon {
  filter: invert(100%);
}

/* If no dark mode user agent stylesheet exists, emulate it */
select,
input,
button,
option {
  color: var(--text-color);
  background-color: var(--background-color);
  border-width: 1px;
  border-radius: 1px;
}

/* Else, use the user agent stylesheet */
@media (prefers-color-scheme: dark) {
  select,
  input,
  button,
  option {
    color: unset;
    background-color: unset;
  }
}