<div class="rotating-text">
  <p>CSS Animation is</p>
  <p>
    <span class="word alizarin">awesome.</span>
    <span class="word wisteria">beautiful.</span>
    <span class="word peter-river">creative.</span>
    <span class="word emerald">fabulous.</span>
    <span class="word sun-flower">interesting.</span>
  </p>
</div>

@import url(https://fonts.googleapis.com/css?family=Lato:600);

body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
  background: #222;
}

.rotating-text {
  font-family: Lato, sans-serif;
  font-weight: 600;
  font-size: 36px;
  color: white;
  transform: translateX(-80px);

  p {
    display: inline-flex;
    margin: 0;
    vertical-align: top;

    .word {
      position: absolute;
      display: flex;
      opacity: 0;

      .letter {
        transform-origin: center center 25px;

        &.out {
          transform: rotateX(90deg);
          transition: 0.32s cubic-bezier(0.6, 0, 0.7, 0.2);
        }
        &.in {
          transition: 0.38s ease;
        }
        &.behind {
          transform: rotateX(-90deg);
        }
      }
    }
  }
}

// palette: https://flatuicolors.com/palette/defo
.alizarin {
  color: #e74c3c;
}

.wisteria {
  color: #8e44ad;
}

.peter-river {
  color: #3498db;
}

.emerald {
  color: #2ecc71;
}

.sun-flower {
  color: #f1c40f;
}

let words = document.querySelectorAll(".word");
words.forEach(word => {
  let letters = word.textContent.split("");
  word.textContent = "";
  letters.forEach(letter => {
    let span = document.createElement("span");
    span.textContent = letter;
    span.className = "letter";
    word.append(span);
  });
});

let currentWordIndex = 0;
let maxWordIndex = words.length - 1;
(words[currentWordIndex] as HTMLElement).style.opacity = "1";

let rotateText = () => {
  let currentWord = words[currentWordIndex];
  let nextWord =
    currentWordIndex === maxWordIndex ? words[0] : words[currentWordIndex + 1];
  // rotate out letters of current word
  Array.from(currentWord.children).forEach((letter, i) => {
    setTimeout(() => {
      letter.className = "letter out";
    }, i * 80);
  });
  // reveal and rotate in letters of next word
  (nextWord as HTMLElement).style.opacity = "1";
  Array.from(nextWord.children).forEach((letter, i) => {
    letter.className = "letter behind";
    setTimeout(() => {
      letter.className = "letter in";
    }, 340 + i * 80);
  });
  currentWordIndex =
    currentWordIndex === maxWordIndex ? 0 : currentWordIndex + 1;
};

rotateText();
setInterval(rotateText, 4000);