* {
  box-sizing: border-box;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
  background: linear-gradient(135deg, #2ea043, #1f6feb);
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100vh;
  margin: 0;
  padding: 15px;
}

.container {
  background: white;
  padding: 20px;
  border-radius: 16px;
  box-shadow: 0 8px 25px rgba(0, 0, 0, 0.3);
  width: 100%;
  max-width: 360px;
  text-align: center;
}

h1 {
  color: #2c3e50;
  font-size: 1.5rem;
  margin: 0 0 10px 0;
}

.score-board {
  background-color: #f6f8fa;
  padding: 8px;
  border-radius: 8px;
  font-size: 1rem;
  font-weight: bold;
  color: #24292e;
  margin-bottom: 12px;
  border: 1px solid #e1e4e8;
}

canvas {
  background-color: #1b2838;
  border-radius: 10px;
  box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.5);
  display: block;
  margin: 0 auto 12px auto;
}

.instruction {
  font-size: 0.8rem;
  color: #57606a;
  margin-bottom: 15px;
  line-height: 1.3;
}

/* Bộ nút điều khiển cảm ứng cho di động */
.controls-dpad {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  margin-bottom: 15px;
}

.horizontal-btns {
  display: flex;
  gap: 12px;
}

.btn-arrow {
  width: 50px;
  height: 45px;
  font-size: 1.2rem;
  background-color: #f3f4f6;
  border: 1px solid #d1d5db;
  border-radius: 8px;
  cursor: pointer;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.btn-arrow:active {
  background-color: #e5e7eb;
  transform: scale(0.95);
}

.btn-main {
  width: 100%;
  padding: 12px;
  font-size: 0.95rem;
  font-weight: bold;
  color: white;
  background-color: #2ea043;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  transition: 0.2s;
}

.btn-main:hover {
  background-color: #2c974b;
}