The timer itself is a CSS animation with 1000 keyframes evenly spread, that runs once for 999s (just realized it should be running for 1000s, oops!). I can't li

The timer itself is a CSS animation with 1000 keyframes evenly spread, that runs once for 999s (just realized it should be running for 1000s, oops!). I can't link to lines in the source code because of the 1.23MB filesize but you can search for "timer" in the raw source to see the relevant code: https://raw.githubusercontent.com/propjockey/css-sweeper/master/index.html https://raw.githubusercontent.com/propjockey/css-sweeper/mas... Here's the part that controls when the animation is running: #level-none:not(:checked) ~ #ram #timer::before { animation: timer step-end 1; animation-duration: 999s; animation-fill-mode: forwards; --pause-if-won: var(--win-state) paused; --pause-if-lost: var(--game-over) paused; --pause-if-randommenu: var(--randommenu-visible) paused; animation-play-state: var(--pause-if-won, var(--pause-if-lost, var(--pause-if-randommenu, running))); } Though the design is responsive to the width of the window, I suspect you mean how slow it is: it's 1.23MB of HTML + CSS, and clicking anything causes almost everything to redraw. It's only a little laggy on my computer but the idea was to test the limits of what's possible and is expected! :) Thank you for checking it out!