ul {
display: flex;
flex-wrap: wrap;
}
ul > li {
flex: 0 0 33.3%;
max-width: 33.3%;
}Для отрисовки снежинок мы создатим холст (Canvas) на весь экран:var canvas = document.createElement('canvas'); canvas.style.position = 'fixed'; canvas.style.top = '0px'; canvas.style.left = '0px'; canvas.style.zIndex = '-10'; canvas.width = document.body.offsetWidth; canvas.height = window.innerHeight; document.body.insertBefore(canvas, document.body.firstChild);
button{
content:"\f190"
}
.toggled button{
content:"\f18e"
}