*{margin:0;padding:0;box-sizing:border-box}body{background:#0f172a;min-height:100vh;display:flex;justify-content:center;align-items:center;font-family:Segoe UI,sans-serif}.game-container{position:relative;width:400px;height:600px;border-radius:20px;overflow:hidden;box-shadow:0 0 40px #38bdf84d;background:linear-gradient(145deg,#0f172a,#1e293b)}.start-screen,.gameover-screen{position:absolute;top:0;right:0;bottom:0;left:0;display:flex;flex-direction:column;align-items:center;justify-content:center;gap:16px;padding:30px;background:#0f172ad9;-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px);z-index:10}.game-canvas{display:block;width:100%;height:100%;touch-action:none}.btn-start{padding:14px 40px;font-size:1.2rem;border:none;border-radius:40px;background:linear-gradient(135deg,#38bdf8,#6366f1);color:#fff;cursor:pointer;box-shadow:0 4px 20px #38bdf866;transition:transform .2s}.btn-start:hover{transform:scale(1.05)}.upgrade-overlay{position:absolute;top:0;right:0;bottom:0;left:0;display:flex;flex-direction:column;align-items:center;justify-content:center;background:#000000b3;-webkit-backdrop-filter:blur(4px);backdrop-filter:blur(4px);z-index:20;gap:20px}.upgrade-overlay h2{font-size:2rem;text-shadow:0 0 20px rgba(34,211,238,.6)}.upgrade-options{display:flex;gap:16px;flex-wrap:wrap;justify-content:center}.upgrade-btn{display:flex;flex-direction:column;align-items:center;gap:6px;padding:16px 28px;border-radius:20px;border:2px solid #38bdf8;background:#38bdf81a;color:#fff;cursor:pointer;transition:all .2s;min-width:100px}.upgrade-btn:hover{background:#38bdf84d;transform:scale(1.08);box-shadow:0 0 20px #38bdf866}.upgrade-icon{font-size:1.8rem}h1{font-size:2.5rem;text-shadow:0 0 30px rgba(56,189,248,.5)}h2{font-size:2rem;color:#ef4444}p{color:#e2e8f0;font-size:1.1rem}