Replay vs. v0.dev: Which AI Handles Complex CSS from Video? (2026)

TL;DR: Replay leverages video input and behavior-driven reconstruction to generate functional UI code, excelling in complex CSS scenarios where screenshot-based tools like v0.dev fall short.

Replay vs. v0.dev: Which AI Handles Complex CSS from Video? (2026)#

The landscape of AI-powered code generation tools is rapidly evolving. While screenshot-to-code solutions have gained traction, they often struggle with dynamic elements, intricate interactions, and, crucially, complex CSS. This is where video-to-code engines like Replay are stepping in, offering a more robust and accurate solution. In this article, we'll compare Replay with v0.dev, a popular AI code generation tool, focusing on their ability to handle complex CSS scenarios, particularly when the input is video.

The Problem with Screenshot-to-Code: A Static View#

Screenshot-to-code tools, like v0.dev, analyze static images to generate UI code. While they can be effective for simple layouts, they inherently lack the ability to understand user behavior, dynamic states, or complex animations. This limitation becomes a significant hurdle when dealing with intricate CSS, which often relies on these very elements. Think about hover effects, transitions, or state changes driven by JavaScript – screenshots simply can't capture them.

Replay: Behavior-Driven Reconstruction from Video#

Replay takes a fundamentally different approach. Instead of relying on static images, Replay analyzes video recordings of user interactions. This "Behavior-Driven Reconstruction" allows Replay to understand the intent behind the UI elements, not just their visual appearance. By understanding how users interact with the interface, Replay can accurately reconstruct the underlying code, including the complex CSS that governs its behavior.

Key Differentiators: Video Input and Behavior Analysis#

The core difference lies in the input method and the analysis performed.

💡 Pro Tip: When evaluating AI code generation tools, always consider the input method. Video provides a richer, more informative source than static images.

Diving into Complex CSS: A Real-World Example#

Let's consider a scenario involving a modal window with a complex animation and custom styling. The modal should fade in, slide up, and have a custom backdrop with a blur effect.

With a screenshot-to-code tool like v0.dev, you might get the basic structure of the modal, but the animation and backdrop effects would likely be missing or poorly implemented. You'd then need to manually add the CSS and JavaScript to achieve the desired behavior.

With Replay, the process is significantly different. By recording a video of the modal being opened, Replay can analyze the animation, identify the CSS properties being modified (e.g.,

, , ), and generate the corresponding code.

Here's an example of the CSS that Replay might generate:

css
/* Modal Container */
.modal-container {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: rgba(0, 0, 0, 0.5); /* Semi-transparent backdrop */
  backdrop-filter: blur(5px); /* Blur effect */
  opacity: 0;
  transition: opacity 0.3s ease-in-out;
  z-index: 1000;
}

/* Modal Content */
.modal-content {
  background-color: white;
  padding: 20px;
  border-radius: 8px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.2);
  transform: translateY(-50px);
  transition: transform 0.3s ease-in-out;
}

/* Modal Open State */
.modal-container.open {
  opacity: 1;
}

.modal-content.open {
  transform: translateY(0);
}

And here's the corresponding JavaScript to toggle the "open" class:

typescript
// Example usage - assuming you have a button to open the modal
const openModalButton = document.getElementById('openModalButton');
const modalContainer = document.getElementById('modalContainer');
const modalContent = document.getElementById('modalContent');

openModalButton.addEventListener('click', () => {
  modalContainer.classList.add('open');
  modalContent.classList.add('open');
});

// Example usage - assuming you have a button to close the modal
const closeModalButton = document.getElementById('closeModalButton');

closeModalButton.addEventListener('click', () => {
  modalContainer.classList.remove('open');
  modalContent.classList.remove('open');
});

This example highlights the power of Replay's behavior analysis. It doesn't just see the modal; it understands how it appears and disappears, and generates the appropriate CSS and JavaScript to replicate that behavior.

⚠️ Warning: While Replay excels at generating complex CSS, it's crucial to review and refine the generated code to ensure optimal performance and maintainability.

Replay's Key Features: Beyond Basic Code Generation#

Replay offers a suite of features that extend beyond basic code generation:

• •Multi-page generation: Reconstruct entire user flows across multiple pages.
• •Supabase integration: Seamlessly integrate with your Supabase backend.
• •Style injection: Inject custom styles to fine-tune the generated UI.
• •Product Flow maps: Visualize and understand the user journey through your application.

Building a Complete UI with Replay: A Step-by-Step Guide#

Let's walk through a simplified example of how to use Replay to reconstruct a UI component from a video:

Step 1: Record the Video#

Record a video of the UI component you want to reconstruct. Make sure to capture all relevant interactions, animations, and state changes.

Step 2: Upload to Replay#

Upload the video to the Replay platform.

Step 3: Analyze and Reconstruct#

Replay will analyze the video and reconstruct the UI code, including HTML, CSS, and JavaScript.

Step 4: Review and Refine#

Review the generated code and make any necessary adjustments. Pay close attention to the CSS to ensure it accurately reflects the desired styling and behavior.

Step 5: Integrate into Your Project#

Integrate the generated code into your project.

📝 Note: The accuracy of the generated code depends on the quality of the video recording and the complexity of the UI component.

The Future of UI Development: Video as the Source of Truth#

Replay represents a significant step towards a future where video becomes the primary source of truth for UI development. By leveraging the power of AI and video analysis, Replay empowers developers to create complex, dynamic UIs with unprecedented speed and accuracy.

Frequently Asked Questions#

Is Replay free to use?#

Replay offers a free tier with limited features and usage. Paid plans are available for more advanced features and higher usage limits.

How is Replay different from v0.dev?#

The key difference lies in the input method and the analysis performed. v0.dev relies on screenshots, while Replay analyzes video recordings. This allows Replay to understand user behavior and generate more accurate and comprehensive code, especially for complex CSS scenarios.

What types of videos work best with Replay?#

Videos with clear, well-defined interactions and minimal distractions work best. Make sure to capture all relevant animations, state changes, and user inputs.

Can Replay generate code for mobile apps?#

Yes, Replay can generate code for both web and mobile applications.

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Ready to try behavior-driven code generation? Get started with Replay - transform any video into working code in seconds.