* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, sans-serif;
}

html, body {
  width: 100%;
  height: 100%;
  background: #0f0f0f;
  color: #fff;
  overflow: hidden;
}

.screen {
  display: none;
  width: 100%;
  height: 100%;
  justify-content: center;
  align-items: center;
  flex-direction: column;
}

.screen.active {
  display: flex;
}

h1 {
  font-size: 3rem;
  margin-bottom: 20px;
}

h2 {
  font-size: 2rem;
  margin-bottom: 10px;
}

button {
  padding: 15px 30px;
  font-size: 1.1rem;
  border: none;
  border-radius: 8px;
  background: #ffffff;
  color: #000;
  cursor: pointer;
}

#game-screen {
  position: relative;
}

#score {
  position: absolute;
  top: 15px;
  left: 15px;
  font-size: 1.2rem;
}

#target {
  width: 80px;
  height: 80px;
  background: #00ff88;
  position: absolute;
  border-radius: 8px;
  display: none;
}

#level {
  position: absolute;
  top: 45px;
  left: 15px;
  font-size: 0.9rem;
  opacity: 0.7;
}

.hit {
  animation: flash 0.1s;
}

@keyframes flash {
  from { background: #00ff88; }
  to   { background: #ffffff; }
}