.christmas-tree {
    position: fixed;
    bottom: 0;
    right: 20px;     /* change to left:20px if needed */
    z-index: 9999;
    width: 260px;     /* adjust size */
    pointer-events: none; /* so it doesn't block clicks */
}
.christmas-tree img {
    filter: drop-shadow(0 0 10px #ff0000)
            drop-shadow(0 0 20px #00ff00)
            drop-shadow(0 0 10px #ffcc00);
}