NEW CSS Scroll Features Will Replace JavaScript

#css #webdev #frontend #performance

Modern CSS That Replaces JavaScript (Part 1) — Scroll-Based Visibility Without JS

This article is the first part of a series where I’ll cover modern CSS features with example that can replace common JavaScript patterns — improving performance, accessibility, and maintainability.

For years, showing or hiding UI elements based on scroll position meant one thing: JavaScript.
Scroll listeners, throttling, performance concerns — we’ve all been there.

But modern CSS is changing that narrative.

With the introduction of scroll-driven container queries, we can now manage scroll-based UI visibility purely with CSS — no JavaScript required.

In this article, we’ll build a “Back to Top” button that appears only when the page is scrollable, using new CSS scroll-state features.

Why This Matters

JavaScript scroll handlers can:

Hurt performance on low-end devices
Add unnecessary complexity
Require debouncing or throttling
Increase bundle size

Modern CSS gives us:

Better performance
Declarative UI behavior
Cleaner and more maintainable code

The Key Concept: scroll-state Container Queries

CSS now allows us to react to scroll conditions using container queries.

We define:

A scroll container
A named scroll state
Conditional styles based on scroll position

Step 1: Define the Scroll Container
CSS

html {
  container-type: scroll-state;
  container-name: page;
  scroll-behavior: smooth;
}

This turns the html element into a scroll-state container named page.

Step 2: Base Page Styling
CSS

html,
body {
  padding: 0;
  margin: 0;
}

.title-header {
  background-color: #4caf50;
  color: white;
  padding: 10px 0;
  text-align: center;
  font-size: 24px;
}

.content {
  max-width: 480px;
  margin: 0 auto;
}

Nothing special here — just layout and typography.

Step 3: Back to Top Button (Hidden by Default)
CSS

.backtotop {
  display: flex;
  position: fixed;
  bottom: 20px;
  right: 20px;
  background: #000066;
  color: #fff;
  padding: 10px 16px;
  border-radius: 30px;
  font-size: 24px;
  text-decoration: none;

  translate: 300px 0;
  transition: translate 0.3s ease-in-out;
}

We move the button off-screen using translate, not display: none, so animations stay smooth.

Step 4: Reveal Button Using Scroll-State Query
CSS

@container page scroll-state(scrollable: top) {
  .backtotop {
    translate: 0 0;
  }
}

What this means:

When the page becomes scrollable
And scrolling is possible from the top
The button slides into view automatically
No JavaScript. No scroll listeners.

HTML Markup

<div class="title-header">
  Manage Visibility on Scroll with NO JS
</div>

<div class="content">
  <h1>NEW CSS Scroll Features Will Replace JavaScript</h1>

  <p>
    Lorem Ipsum is simply dummy text of the printing and typesetting industry...
  </p>

  <!-- Long content continues -->
</div>

<a href="#top" class="backtotop">Move to top</a>

Code pen Live Example

Github Code Repo

Why This Is a Big Deal

✅ Zero JavaScript
✅ Better performance
✅ Declarative UI logic
✅ Cleaner codebase
✅ Perfect for modern design systems

This approach is especially powerful for: