* {
  border: 0;
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
:root {
  --hue: 223;
  --bg: hsl(var(--hue),10%,90%);
  --fg: hsl(var(--hue),10%,10%);
  --primary: hsl(var(--hue),90%,55%);
  --shadow: hsl(var(--hue),90%,35%);
  font-size: calc(20px + (40 - 20) * (100vw - 320px) / (1280 - 320));
}
body {
  background: var(--bg);
  color: var(--fg);
  font: 1em/1.5 Spartan, sans-serif;
  height: 100vh;
  display: grid;
  place-items: center;
}
.clock {
  background-color: var(--primary);
  background-image: linear-gradient(-45deg,hsla(var(--hue),10%,10%,0),hsla(var(--hue),10%,10%,0.2));
  border-radius: 0.25rem;
  box-shadow: 0 0 0 0.1rem hsla(var(--hue),10%,10%,0.2) inset;
  color: hsl(var(--hue),10%,100%);
  display: flex;
  justify-content: center;
  font-size: 2em;
  line-height: 1;
  padding: 0.25rem 0.5rem;
}
.clock__digit {
  display: inline-block;
  font-weight: bold;
  text-align: center;
  text-shadow:
    0 0 0 var(--shadow),
    0 0 0 var(--shadow),
    1px 1px 0 var(--shadow),
    2px 2px 0 var(--shadow),
    3px 3px 0 var(--shadow),
    3px 3px 0 var(--shadow),
    4px 4px 0 var(--shadow);
  width: 1ch;
}
.clock__digit:not(:nth-child(3n)) {
  margin-top: 0.25rem;
}
.clock__digit--bounce {
  animation: bounce 0.5s ease-in;
}

/* Dark theme */
@media (prefers-color-scheme: dark) {
  :root {
    --bg: hsl(var(--hue),10%,10%);
    --fg: hsl(var(--hue),10%,90%);
  }
}

/* Animations */
@keyframes bounce {
  from, to {
    animation-timing-function: ease-in;
    text-shadow:
      0 0 0 var(--shadow),
      0 0 0 var(--shadow),
      1px 1px 0 var(--shadow),
      2px 2px 0 var(--shadow),
      3px 3px 0 var(--shadow),
      3px 3px 0 var(--shadow),
      4px 4px 0 var(--shadow);
    transform: translate(0,0);
  }
  33% {
    animation-timing-function: ease-out;
    text-shadow:
      0 0 0 var(--shadow),
      0 0 0 var(--shadow),
      0 0 0 var(--shadow),
      0 0 0 var(--shadow),
      0 0 0 var(--shadow),
      1px 1px 0 var(--shadow);
    transform: translate(4px,4px);
  }
  67% {
    animation-timing-function: ease-in;
    text-shadow:
      1px 1px 0 var(--shadow),
      2px 2px 0 var(--shadow),
      3px 3px 0 var(--shadow),
      4px 4px 0 var(--shadow),
      5px 5px 0 var(--shadow),
      6px 6px 0 var(--shadow);
    transform: translate(-2px,-2px);
  }
}

window.addEventListener("DOMContentLoaded",() => {
  const clock = new BouncyEmbossedClock(".clock");
});

class BouncyEmbossedClock {
  constructor(el) {
    this.el = document.querySelector(el);
    this.els = this.el ? this.el.querySelectorAll(".clock__digit") : [];
    this.digits = [];
    this.to = null;
    this.dto = [
      [null,null,null],
      [null,null,null],
      [null,null],
      [null,null,null],
      [null,null,null],
      [null,null],
      [null,null,null],
      [null,null,null],
    ];
    this.staticUpdate();
    this.update();
  }
  getTime() {
    const time = new Date();
    const hms = [
      time.getHours(),
      time.getMinutes(),
      time.getSeconds()
    ];

    return hms.map(u => u < 10 ? `0${u}` : `${u}`).join(":").split(""); 
  }
  staticUpdate() {
    if (this.els) {
      this.digits = this.getTime();
      this.digits.forEach((d,i) => {
        this.els[i].textContent = d;
      });
    }
  }
  update() {
    if (this.els) {
      // get the time
      const display = this.getTime();
      const bounce = "clock__digit--bounce";
      const baseDelay = 350;
      const delayDec = 50;

      // display the digits
      display.forEach((d,i) => {
        if (+d > +this.digits[i] || +d === 0 && +this.digits[i] !== 0) {
          const colonElCL = display[i + 1] === ":" ? this.els[i + 1].classList : null;
          const el = this.els[i];
          const timeout = baseDelay - delayDec * i;

          this.dto[i].forEach(t => {
            clearTimeout(t);
          });

          // run the animation
          this.dto[i][0] = setTimeout(() => {
            el.classList.add(bounce);
          }, timeout);

          // show the next digit
          this.dto[i][1] = setTimeout(() => {
            el.textContent = d;
          }, timeout + 167);

          // kill the animation
          this.dto[i][2] = setTimeout(() => {
            el.classList.remove(bounce);
          }, timeout + 500);

          // colon animation (if applicable)
          if (colonElCL) {
            this.dto[i + 1].forEach(t => {
              clearTimeout(t);
            });

            this.dto[i + 1][0] = setTimeout(() => {
               colonElCL.add(bounce);
            }, timeout - delayDec);

            this.dto[i + 1][1] = setTimeout(() => {
               colonElCL.remove(bounce);
            }, (timeout - delayDec) + 500);
          }
        }

        this.digits[i] = d;
      });

      // loop
      clearTimeout(this.to);
      this.to = setTimeout(this.update.bind(this),1e3);
    }
  }
}