* {
  box-sizing: border-box;
}
body,
html {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: linear-gradient(to bottom, #00aaff, #004488);
  font-family: sans-serif;
}
#gameCanvas {
  display: block;
  width: 100%;
  height: 100%;
  background: transparent;
  touch-action: none; 
}
#controls {
  position: fixed;
  bottom: 20px;
  left: 20px;
  display: grid;
  grid-template-areas:
    ". up ."
    "left . right"
    ". down .";
  grid-gap: 10px;
  z-index: 10;
}
#btn-up {
  grid-area: up;
}
#btn-left {
  grid-area: left;
}
#btn-down {
  grid-area: down;
}
#btn-right {
  grid-area: right;
}
#controls button {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  border: none;
  background: rgba(0, 0, 0, 0.5);
  color: white;
  display: flex;
  align-items: center;
  justify-content: center;
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
}
#controls button:active {
  background: rgba(0, 0, 0, 0.8);
}
#score {
  position: fixed;
  top: 20px;
  right: 20px;
  font-size: 24px;
  color: white;
  background: rgba(0, 0, 0, 0.5);
  padding: 10px;
  border-radius: 10px;
  z-index: 10;
}

#copyright {
  position: fixed;
  bottom: 10px;
  right: 10px;
  font-size: 12px;
  color: white;
  text-shadow: 1px 1px 2px black;
  z-index: 10;
}

#paypal-button {
  position: fixed;
  top: 20px;
  left: 20px;
  z-index: 10;
  border-radius: 20px;
  overflow: hidden;
  background: #0070BA;
  padding: 10px 15px;
  display: flex;
  align-items: center;
  text-decoration: none;
  box-shadow: 0 4px 8px rgba(0,0,0,0.2);
  transition: all 0.3s ease;
}

#paypal-button:hover {
  background: #003087;
  transform: translateY(-2px);
  box-shadow: 0 6px 12px rgba(0,0,0,0.3);
}

#paypal-button span {
  color: white;
  font-weight: bold;
  margin-left: 8px;
}