void setup() {
  // PB2, PB3 output (LEDs)
  // PB0, PB1 input (knoppen)
  DDRB = 0b00001100;
  //       xx1312111098

  // pull-up enkel op knop 1 (PB0)
  PORTB = 0b00000001;
}

void loop() {
  // knop 1 → LED 1
  if (!(PINB & (1 << 0))) {
    PORTB |= (1 << 2);
  } else {
    PORTB &= ~(1 << 2);
  }

  // knop 2 → LED 2
  if (PINB & (1 << 1)) {
    PORTB |= (1 << 3);
  } else {
    PORTB &= ~(1 << 3);
  }
}