style.css

/* GENERAL STYLING */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

input,
textarea,
button,
select,
a,
a:link,
a:visited,
a:hover,
a:active {
  -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
  text-decoration: none;
}

/* BODY */
body {
  font-family: 'Press Start 2P', cursive;
  width: 100%;
  height: 100vh;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
  background: linear-gradient(to top, rgb(121, 121, 124), rgb(190, 190, 192));
  overflow: hidden;
}

/* TITLE */
.title {
  margin-bottom: 50px;
  font-size: 2.3rem;
  text-transform: uppercase;
  color: rgb(158, 6, 69);
  animation: blink 1s infinite;
  animation-timing-function: steps(2);
}

@keyframes blink {
  100% {
    color: rgb(8, 1, 4);
  }
}

/* GAME CANVAS */
.canvas {
  position: relative;
  width: 350px;
  height: 350px;
  background: rgb(130, 197, 6);
  border-radius: 10px;
  box-shadow: inset -10px -10px 50px rgba(0, 0, 0, 0.205),
    inset 10px 10px 50px rgba(255, 255, 255, 0.226),
    1px 1px 10px rgba(0, 0, 0, 0.342), -1px -1px 10px rgba(255, 255, 255, 0.548);
  animation: shine 15s linear infinite;

  overflow: hidden;
}

@keyframes shine {
  0% {
    background: rgb(130, 197, 6);
  }

  50% {
    background: rgb(109, 165, 4);
  }

  0% {
    background: rgb(130, 197, 6);
  }
}

/* PLAYER */
.player {
  position: absolute;
  background: rgb(57, 87, 1);
  width: 20px;
  height: 20px;
  bottom: 30px;
  left: 160px;
  animation: player-waiting 0.9s infinite;
}

@keyframes player-waiting {
  50% {
    transform: translateY(6px);
  }
}

/* ENEMY */
.enemy {
  position: absolute;
  background: rgb(85, 129, 3);
  width: 60px;
  height: 20px;
  left: 0px;
  top: -30px;
}

/* PLAY BUTTON */
.play-button {
  font-family: 'Press Start 2P', cursive;
  text-transform: uppercase;
  margin-top: 30px;
  font-size: 1rem;
  background: rgb(48, 47, 47);
  color: #fff;
  border: none;
  padding: 0.5rem 2rem;
  border-radius: 3px;
  outline: none;
}

.play-button:hover {
  background: rgb(66, 65, 65);
}

.play-button:active {
  transform: scale(0.9);
  background: rgb(0, 0, 0);
}

/* GAME OVER TEXT */
.game-over-text {
  position: absolute;
  font-size: 1.25rem;
  left: 65px;
  top: calc(150px - 1.25rem);
  text-transform: uppercase;
  color: rgb(54, 80, 1);
  background: rgba(255, 255, 255, 0.212);
  padding: 0.4rem 0.4rem;
  animation: game-over-blink 1s steps(2) infinite;
  display: none;
}

.game-over-score-text {
  position: absolute;
  font-size: 1.25rem;
  left: 65px;
  top: calc(150px + 2rem);
  text-transform: uppercase;
  color: rgb(54, 80, 1);
  padding: 0.4rem 0.4rem;
  display: none;
}

@keyframes game-over-blink {
  0% {
    visibility: hidden;
  }

  100% {
    visibility: visible;
  }
}

/* HOW TO TEXT */
.how-to-text {
  position: relative;
  padding: 3rem;
}

.how-to-text p {
  font-size: 0.875rem;
  max-width: 30ch;
  line-height: 1.5rem;
  color: rgb(48, 75, 1);
}

/* SCORE TEXT */
.score-text {
  position: absolute;
  color: rgba(0, 0, 0, 0.404);
  top: 10px;
  left: 8px;
}