styles.css

body {
  padding-top: 10vh;
  margin: 0 auto;
  width: 75%;
  height: 100vh;
  box-sizing: border-box;
  text-align: center;
  background-color: whitesmoke;
}

input, button {
  width: 5vh;
  height: 5vh;
  margin: 0;
  font-size: 24px;
  background-color: wheat;
  border: 1px solid goldenrod;
  border-radius: 5px;
}

hr {
  width: 0;
}

#word {
  font-size: 64px;
  margin: 20px;
  color: saddlebrown;
}

#next {
  width: initial;
}

#feedback {
  font-size: 32px;
  font-weight: bold;
}

#progress {
  margin-top: 30px;
}

#feedback::before,
#progress > span::before {
  content: "?";
}

#progress > span {
  display: inline-block;
  width: 15px;
  font-weight: bold;
  font-size: 16px;
}

#feedback.correct::before,
#progress > span.correct::before {
  content: "✔";
  color: lime;
}

#feedback.wrong::before,
#progress > span.wrong::before {
  content: "✘";
  color: red;
}