Attiny13 flashlight fade in and out at button press

Flashlight-fade.ino

#include <avr/interrupt.h>
#include <avr/sleep.h>

#define BUTTON 4
#define LED 1

int dir = 1;
int lum = 0;
boolean toggle = false;
int vals [] = {0, 1, 2, 3, 5, 9, 12, 18, 22, 32, 44, 58, 76, 120, 163, 255};

void setup() {
  pinMode(BUTTON, INPUT);
  pinMode(LED, OUTPUT);

  // These two allow us to save ~25% of total energy
  ADCSRA &= ~(1<<ADEN); //Disable ADC
  ACSR = (1<<ACD); //Disable the analog comparator
}

void loop() {
  if (digitalRead(BUTTON) == HIGH) {
    toggle = true;
    lum += dir;
    if ((lum >= 0) && (lum < 16))
      analogWrite(LED, vals[lum]);
    delay(100);
  } else { // toggle direction
    if (toggle) {
      dir = -1 * dir;
      toggle = false;
    }
  }
}