* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Courier New', monospace;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    color: #fff;
}

.game-container {
    text-align: center;
    background: rgba(0, 0, 0, 0.3);
    padding: 2rem;
    border-radius: 1rem;
    box-shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
}

h1 {
    font-size: 2.5rem;
    margin-bottom: 1rem;
    text-shadow: 2px 2px 4px rgba(0, 0, 0, 0.5);
    color: #ffd700;
}

#gameCanvas {
    border: 4px solid #ffd700;
    border-radius: 0.5rem;
    background: #1a1a2e;
    display: block;
    margin: 0 auto;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.5);
}

.controls {
    margin-top: 1rem;
    font-size: 1rem;
    opacity: 0.9;
}

.controls p {
    margin: 0.5rem 0;
}

/* 22.1: Screen-reader only utility */
.sr-only {
    position: absolute;
    width: 1px;
    height: 1px;
    padding: 0;
    margin: -1px;
    overflow: hidden;
    clip: rect(0, 0, 0, 0);
    white-space: nowrap;
    border: 0;
}

/* 22.2: Mobile hint banner */
.mobile-hint {
    margin-bottom: 0.75rem;
    padding: 0.5rem 1rem;
    background: rgba(255, 200, 0, 0.2);
    border: 1px solid rgba(255, 200, 0, 0.5);
    border-radius: 0.5rem;
    font-size: 0.9rem;
    color: #ffe066;
}

/* 22.1: Visible focus ring for keyboard navigation */
#gameCanvas:focus {
    outline: 3px solid #FFD700;
    outline-offset: 2px;
}

@media (max-width: 900px) {
    .game-container {
        padding: 1rem;
    }
    
    h1 {
        font-size: 2rem;
    }
    
    #gameCanvas {
        max-width: 100%;
        height: auto;
    }
}