Generated by SassMeister.com.

SassMeister-input.scss

// ----
// libsass (v3.2.5)
// ----

.alert_signup {
  .alertMessage {
    .with-left-rail &:before {
      /* Desired */
      color: #fff;
    }
    

    .with-left-rail:before {
      /* Not Desired */
      color: #fff;
    }
  }
}

SassMeister-output.css

.with-left-rail .alert_signup .alertMessage:before {
  /* Desired */
  color: #fff;
}

.alert_signup .alertMessage .with-left-rail:before {
  /* Not Desired */
  color: #fff;
}