:root {
  --bg-night: #091220;
  --bg-sea: #17385f;
  --bg-mint: #2a6f8f;
  --frame: #d7ebf8;
  --panel: rgba(10, 19, 36, 0.56);
}

* {
  box-sizing: border-box;
}

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

body {
  font-family: "Trebuchet MS", "Segoe UI", sans-serif;
  background:
    radial-gradient(circle at 20% 15%, rgba(83, 163, 198, 0.42), transparent 32%),
    radial-gradient(circle at 85% 78%, rgba(24, 88, 126, 0.36), transparent 34%),
    linear-gradient(150deg, var(--bg-night), var(--bg-sea) 52%, var(--bg-mint));
  color: #f5fbff;
  overflow: hidden;
}

#game-shell {
  width: 100%;
  height: 100%;
  padding: clamp(10px, 2vw, 24px);
  display: flex;
  align-items: center;
  justify-content: center;
}

#game-root {
  width: 100%;
  height: 100%;
  border: 2px solid rgba(215, 235, 248, 0.55);
  border-radius: 16px;
  overflow: hidden;
  background: linear-gradient(180deg, rgba(16, 31, 58, 0.85), var(--panel));
  box-shadow:
    0 22px 60px rgba(4, 7, 16, 0.55),
    inset 0 0 0 1px rgba(215, 235, 248, 0.12);
}

#game-root canvas {
  display: block;
  margin: 0 auto;
}

@media (max-width: 768px) {
  #game-shell {
    padding: 8px;
  }

  #game-root {
    border-radius: 10px;
  }
}