A “slider”, as in, a bunch of boxes set in a row that you can navigate between. You know what a slider is. There are loads of features you may want in a slider. Just as one example, you might want the slider to be swiped or scrolled. Or, you might not want that, and to have the slider only respond to click or tappable buttons that navigate to slides. Or you might want both. Or you might want to combine all that with autoplay.
What are more limitations?
We’ve about tapped out what HTML and CSS alone can do here.
Need autoplay? You might be able to do something rudimentary with a checkbox, :checked, and controlling the animation-play-state of a @keyframes animation, but it will feel limited and janky.
Want to have it infinitely scroll in one direction, repeating as needed? That’s going to require cloning and moving stuff around in the DOM. Or perhaps some gross misuse of <marquee>.