html,
body {
  height: 100%;
  margin: 0;
}

body {
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  cursor: pointer;
}

.container {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100%;
}

#score {
  position: absolute;
  top: 30px;
  right: 30px;
  font-size: 2em;
  font-weight: 900;
}

#introduction {
  width: 200px;
  height: 150px;
  position: absolute;
  font-weight: 600;
  font-size: 0.8em;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  text-align: center;
  transition: opacity 2s;
}

#restart {
  width: 120px;
  height: 120px;
  position: absolute;
  border-radius: 50%;
  color: white;
  background-color: red;
  border: none;
  font-weight: 700;
  font-size: 1.2em;
  font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
  display: none;
  cursor: pointer;
}

#perfect {
  position: absolute;
  opacity: 0;
  transition: opacity 2s;
}

#level-notification {
  position: absolute;
  font-size: 3em;
  font-weight: 900;
  color: white;
  text-shadow: 2px 2px 10px rgba(0,0,0,0.8);
  opacity: 0;
  transition: opacity 0.5s;
  pointer-events: none;
  z-index: 100;
}

#sound-toggle {
  position: absolute;
  top: 30px;
  left: 30px;
  font-size: 1.5em;
  background: rgba(255, 255, 255, 0.15);
  backdrop-filter: blur(5px);
  -webkit-backdrop-filter: blur(5px);
  border: 1px solid rgba(255, 255, 255, 0.2);
  border-radius: 50%;
  width: 50px;
  height: 50px;
  display: flex;
  justify-content: center;
  align-items: center;
  color: white;
  cursor: pointer;
  box-shadow: 0 4px 15px rgba(0, 0, 0, 0.2);
  transition: all 0.3s ease;
  user-select: none;
  -webkit-user-select: none;
  z-index: 1000;
}

#sound-toggle:hover {
  background: rgba(255, 255, 255, 0.3);
  transform: scale(1.1);
}

#sound-toggle:active {
  transform: scale(0.95);
}