body {
    margin: 0;
    overflow: hidden; /* Prevent scrollbars */
    background-color: #f0f0f0;
    /* Ensure body takes full height for accurate boundary calculation */
    min-height: 100vh;
    position: relative; /* Needed for absolute positioning of balls */
}

.ball {
    position: absolute;
    border-radius: 50%; /* Make it round */
    /* box-shadow: 2px 2px 5px rgba(0,0,0,0.3); */ /* Optional shadow */
    will-change: transform; /* Hint for performance */
}