body, html {
    margin: 0;
    padding: 0;
    overflow: hidden;
    background: #000;
    font-family: 'Courier New', monospace;
}

canvas {
    position: absolute;
    top: 0;
    left: 0;
}

#overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: #000;
    opacity: 0;
    transition: opacity 2s;
}

#startScreen {
    position: absolute;
    width: 100%;
    height: 100%;
    display: flex;
    flex-direction: column;
    justify-content: center;
    align-items: center;
    background: radial-gradient(circle at center, #0a0a2e 0%, #000 100%);
    z-index: 200;
    transition: opacity 0.8s;
}

#startScreen.hidden {
    opacity: 0;
    pointer-events: none;
}

.title {
    font-size: 48px;
    color: #00ffff;
    text-shadow: 0 0 20px #00ffff, 0 0 60px #0099ff;
    margin-bottom: 20px;
    letter-spacing: 4px;
    animation: pulse 2s infinite;
    text-align: center;
}

.subtitle {
    font-size: 18px;
    color: #66d9ff;
    text-shadow: 0 0 10px #00ffff;
    margin-bottom: 50px;
    letter-spacing: 2px;
    text-align: center;
}

#startBtn {
    padding: 20px 50px;
    font-size: 20px;
    background: linear-gradient(135deg, #00ffff, #0099ff, #6600ff);
    color: #000;
    border: 2px solid #00ffff;
    border-radius: 50px;
    cursor: pointer;
    letter-spacing: 3px;
    box-shadow: 0 0 30px #00ffff;
    transition: 0.3s;
    position: relative;
    overflow: hidden;
}

#startBtn:hover {
    transform: scale(1.1);
}

#startBtn::before {
    content: '';
    position: absolute;
    width: 200%;
    height: 200%;
    background: linear-gradient(45deg, transparent, rgba(255,255,255,0.3), transparent);
    animation: shimmer 3s infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; }
    50% { opacity: 0.8; }
}

@keyframes shimmer {
    0% { transform: translate(-100%, -100%); }
    100% { transform: translate(100%, 100%); }
}

.stars {
    position: absolute;
    width: 100%;
    height: 100%;
}

.star {
    position: absolute;
    width: 2px;
    height: 2px;
    background: white;
    border-radius: 50%;
    animation: twinkle 3s infinite;
}

@keyframes twinkle {
    0%, 100% { opacity: 0.3; }
    50% { opacity: 1; }
}

/* Responsive */
@media (max-width: 768px) {
    .title { font-size: 32px; }
    .subtitle { font-size: 14px; }
}