.lang-btn {
  padding: 4px 14px;
  font-family: monospace; font-size: 12px; font-weight: 700;
  letter-spacing: 2px; cursor: pointer;
  border-radius: 5px;
  border: 1px solid rgba(255,255,255,0.2);
  background: rgba(0,229,255,0.04); color: #9bb6c4;
  transition: all 0.15s;
  margin-left: 4px;
}
.lang-btn.active {
  border-color: #39ff14; color: #39ff14;
  background: rgba(57,255,20,0.08);
}
.lang-btn:not(.active):hover {
  border-color: rgba(255,255,255,0.4); color: #d9f7ff;
}

body { margin: 0; overflow: hidden; background: #000; }
#app-shell {
  position: fixed;
  inset: 0;
  overflow: hidden;
  background: #000;
}
#app-shell:fullscreen,
#app-shell:-webkit-full-screen {
  width: 100vw;
  height: 100vh;
}
#app-shell #game-scene {
  width: 100%;
  height: 100%;
}
.hidden { display: none !important; }