:root { --bg: #1a1a1a; --text: #4caf50; }
* { box-sizing: border-box; margin: 0; padding: 0; }
body { font-family: 'Outfit', sans-serif; background: var(--bg); color: var(--text); min-height: 100vh; display: flex;
    flex-direction: column; justify-content: flex-start; align-items: center; overflow: hidden;}
.game-container { width: 100%; max-width: 500px; padding: 1rem; display: flex; flex-direction: column; align-items: center; position: relative;}
header { width: 100%; display: flex; justify-content: space-between; align-items: center; margin-bottom: 1rem; }
.back-btn { text-decoration: none; background: #03a9f4; color: white; padding: 10px 20px; border-radius: 20px; font-weight: bold; box-shadow: 0 4px 0 #0288d1; }
.back-btn:active { transform: translateY(4px); box-shadow: 0 0 0; }
h1 { font-size: 2rem; color: #0288d1; text-shadow: 2px 2px 0 #000; }
.hud { font-size: 1.5rem; font-weight: 900; margin-bottom: 1rem; }
.instruction { font-size: 1.2rem; margin-top: 1rem; font-weight: bold; text-align: center; color: #0277bd;}

.game-area { width: 100%; height: 400px; background: #81d4fa; border-radius: 15px; position: relative; overflow: hidden; box-shadow: 0 10px 30px rgba(0,0,0,0.1); border: 4px solid #fff; }
.bird { position: absolute; left: 50px; top: 150px; font-size: 3rem; z-index: 2; transition: transform 0.1s;}
.pipe { position: absolute; background: #4caf50; width: 60px; right: -60px; border: 3px solid #388e3c; border-radius: 5px; }

.overlay { position: absolute; inset: 0; background: rgba(30,30,30,0.95); display: flex; flex-direction: column; justify-content: center; align-items: center; z-index: 10; border-radius: 10px; }
.overlay h2 { font-size: 2.5rem; color: #f44336; margin-bottom: 1rem; text-shadow: 2px 2px 0 #000;}
.btn { background: #4caf50; border: none; padding: 15px 40px; font-size: 1.5rem; font-weight: 900; border-radius: 50px; cursor: pointer; color: white; font-family: 'Outfit'; box-shadow: 0 5px 0 #388e3c; }
.btn:active { transform: translateY(5px); box-shadow: none; }
.hidden { display: none !important; }