* {
  padding: 0;
  margin: 0;
  box-sizing: border-box;
  text-decoration: none;
  list-style: none;
}

:root {
  --bg-color: #000000;
  --text-color: #fff;
  --red-color: #ff0000;
  --green-color: #008000;
  --blue-color: #0000ff;
  --yellow-color: #ffff00;
  --orange-color: #ffa600;
  --purple-color: #500073;
  --pink-color: #ffcfcf;
  --white-color-50: #ffffff0a;
  --gray-color: #a9a9a9;



  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;

  --font-size-smx: 12px;
  --font-size-sm: 14px;
  --font-size-md: 16px;
  --font-size-lg: 20px;
  --font-size-xl: 24px;
  --font-size-2xl: 30px;
}

i {
  cursor: pointer;
}

.sound.on::after {
  display: block;
  content: url(assets/svg/sound-on.svg);
  width: 28px;
  aspect-ratio: 1/1;
}

.sound.mute::after {
  display: block;
  content: url(assets/svg/sound-mute.svg);
  width: 28px;
  aspect-ratio: 1/1;
}

body {
  background: var(--bg-color);
}

#level_title {
  font-family: "Press Start 2P", cursive;
  font-size: var(--font-size-md);
  padding: 10px 0;
  color: var(--text-color);
  cursor: default;
}

.flex {
  display: flex;
  justify-content: space-between;
  align-items: center;
}

.container {
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  height: 90vh;
  padding: 2vh;
}

.container-helper {
  width: 100%;
  max-width: 455px;
}

.row {
  display: grid;
  grid-template-columns: 1fr 1fr 1fr 1fr;
  gap: 10px;
}

.btn {
  width: 100%;
  border: 2px solid var(--white-color-50);
  border-radius: 10%;
  aspect-ratio: 1/1;
  cursor: pointer;
  opacity: 0.5;

  &:hover {
    opacity: 0.7;
  }

  &.active {
    opacity: 1;
  }
}

.game-over {
  background: var(--red-color);
}

.red {
  background: var(--red-color);
}

.green {
  background: var(--green-color);
}

.blue {
  background:var(--blue-color);
}

.yellow {
  background: var(--yellow-color);
}

.orange {
  background: var(--orange-color);
}

.gray {
  background: var(--gray-color);
}

.purple {
  background: var(--purple-color);
}

.pink {
  background: var(--pink-color);
}