Generated by SassMeister.com.

SassMeister-input.sass

// ----
// Sass (v3.4.12)
// Compass (v1.0.3)
// ----

=replace-with-icon($x)
    pretend-icon: $x
$icon-settings: 'settings-image'
$icon-settings_dark: 'settings-image--dark'

button
    &.-toggle_menu
        +replace-with-icon($icon-settings)
        background-size: 19px
        background-position: 12px 15px
        body[data-theme="night"] &
            +replace-with-icon($icon-settings_dark)
            background-size: 19px
            background-position: 12px 15px

SassMeister-output.css

button.-toggle_menu {
  pretend-icon: "settings-image";
  background-size: 19px;
  background-position: 12px 15px;
}
body[data-theme="night"] button.-toggle_menu {
  pretend-icon: "settings-image--dark";
  background-size: 19px;
  background-position: 12px 15px;
}