Scroll Timeline Playground - Online Scroll‑Driven Animation
Create an animation that advances with scroll using animation‑timeline: scroll(). See the visual timeline editor. Modern CSS.
UD5 Toolkit
Generate a sleek, pure CSS scroll progress indicator — lightweight, customizable, and copy‑ready.
Scroll progress bars have become an essential UX pattern on modern websites. They give readers a clear sense of how much content remains, reducing bounce rates and improving engagement. Studies show that users are 37% more likely to finish reading an article when a visual progress indicator is present.
The concept is beautifully simple — a slim bar fixed to the top (or bottom) of the viewport that fills as the user scrolls. What makes it elegant is that it requires zero JavaScript in modern browsers, thanks to the new CSS animation-timeline property.
Introduced as part of the Scroll-Driven Animations specification, animation-timeline: scroll(root) lets you bind a CSS animation directly to the scroll position of the document. This means the browser handles everything natively — no event listeners, no requestAnimationFrame, no performance overhead.
Of course, browser support is still evolving. As of 2025, Chromium-based browsers (Chrome, Edge, Opera, Brave) fully support scroll-driven animations. Firefox has the feature behind a flag, and Safari support is in development. For production sites, a progressive enhancement approach is recommended — use the CSS-only method as the primary implementation, with a tiny JavaScript fallback for unsupported browsers.
The progress bar you see above this text is a live demonstration. Scroll down within this preview window and watch the bar grow. Try tweaking the settings on the left — change colors, height, position, and effects — and see the changes instantly.
Beyond the obvious UX benefit, progress indicators subtly encourage users to scroll further. They tap into the psychological principle of goal gradient effect — the closer people get to a goal, the more motivated they become to complete it. A progress bar makes "finishing the article" a tangible goal.
Additionally, for content-heavy websites, scroll progress bars serve as a non-intrusive navigation aid. They answer the silent question every reader has: "How much more is there?"
One of the biggest advantages of the CSS-only approach is performance. Traditional JavaScript-based progress bars require listening to the scroll event, which can fire hundreds of times per second. Without proper throttling, this can cause jank and hurt Core Web Vitals scores — especially the Interaction to Next Paint (INP) metric.
With animation-timeline, the browser's compositor handles everything off the main thread. The result is buttery-smooth 60fps animations that don't interfere with user interactions or page responsiveness.
Try customizing your progress bar now! Use the controls on the left to adjust colors, height, position, and special effects. The generated CSS code below updates in real-time — just copy and paste it into your project.
animation-timeline property. By setting animation-timeline: scroll(root), you can bind a @keyframes animation directly to the scroll position of the document root element.scaleX(0) to scaleX(1) animation tied to the scroll timeline will naturally progress as the user scrolls — no JavaScript required. The browser's compositor handles the animation off the main thread, ensuring smooth 60fps performance.animation-timeline: scroll().layout.css.scroll-driven-animations.enabled flag (expected to ship fully in an upcoming release).scroll event can cause jank if not properly throttled with requestAnimationFrame or IntersectionObserver. The pure CSS method is objectively superior for performance.
<style> tag in your <head>).<div class="scroll-progress"></div> element just inside your <body> tag.animation-timeline yet, consider adding a small JavaScript polyfill for graceful degradation.
Create an animation that advances with scroll using animation‑timeline: scroll(). See the visual timeline editor. Modern CSS.
See how overflow: visible, hidden, scroll, and auto behave with real content. Clone to test with your text.
Define the initial scroll position for a scroll container with scroll‑start. Test with and without snapping. New feature.
Enter a router's MAC address or serial and generate the common default WPA passphrase for major ISP brands. Educational purpose only.
Design a layout where nested grids share track sizes with their parent via subgrid. Copy the complete CSS.
Pick colors for the shadcn/ui design system and generate the complete CSS variable theme file. Copy into your project.
Paste your CSS and see warnings for properties that have limited browser support. Links to CanIUse. Modernize safely.
Format a list of Q&A pairs and export as a CSV ready for Anki import. Simple line‑based template. Local.
Style underlines, overlines, and strike-throughs with colors, wavy styles, and thickness. Modern CSS text‑decoration.
Generate a random medieval occupation with a short description. For NPCs or historical curiosity. Local list.
Generate a hardboiled film noir plot with a detective, a dame, and a McGuffin. Great for creative writing prompts.
Generate a grand, aristocratic title like 'Duke of Waffleshire'. Perfect for silly fun or RPG characters. Local.
Design a button or card that glows on hover. Adjust shadow color, spread, and transition. Copy the CSS. Rich UI.
Create a realistic letterpress (debossed) text effect using CSS text‑shadow and background. Adjust depth and light direction. Copy code.
Generate a realistic‑sounding dinosaur name and see a fun description. Perfect for kids and writers.
Generate a subtle noise/grain texture as a CSS background pattern. Adjust opacity and size. For that film look.
Generate random but realistic‑looking data arrays (users, products, orders) with typos and missing fields. For test robustness.
Create a customizable checkerboard or grid background using pure CSS gradients. Adjust cell size and colors. Copy the code.
Create a custom HTML/CSS progress bar with percentage, colors, and animation. Copy the code. Modern UI element.
Fill in a few details and get a polished resignation letter. No data stored. Instant copy or print.
Paste plain text and turn it into a nested outline using indent levels or Markdown headings. Great for planning.
Upload a small pixel art image and get a CSS grid layout that recreates it using divs. Novelty developer tool.
Convert short text into a black‑and‑white Braille bump image ready for embossing. Educational and inclusive.
Generate a random, somewhat meaningful song lyric line. Write your own hit with AI‑free randomness. All local.
A replica of the famous Flexbox Froggy game: solve alignment puzzles by writing CSS. Progress saved locally. Fun frontend learning.
Generate a realistic‑sounding exoplanet designation (e.g., Kepler‑442b) and a sci‑fi planet description. For worldbuilding.
Create a realistic‑looking fake tweet with any name, handle, text, likes, and retweets. Just for laughs. All local canvas.
Generate magic squares of odd order (3x3, 5x5, …). See the sum constant and verify rows, columns, diagonals. Educational math toy.
One click to get a hilarious excuse for being late, missing homework, or not doing chores. Pure comedy.
Design a realistic-looking fake receipt with custom store name, items, and total. For jokes and gags. No real transaction.