How to Extract Production-Grade Typography and Spacing Scales from Any Video File

Designers and developers waste thousands of hours every year manually measuring pixels in Figma or inspecting CSS in Chrome DevTools to rebuild what already exists. This manual extraction is the primary bottleneck in the $3.6 trillion global technical debt crisis. When you need to migrate a legacy application or build a design system from an existing product, you don't need a screenshot; you need the temporal context of a video.

Video-to-code is the process of using computer vision and large language models (LLMs) to transform screen recordings into functional, production-ready source code. Replay (replay.build) pioneered this approach by capturing 10x more context from video than static images, allowing teams to extract productiongrade typography spacing with mathematical precision.

TL;DR: Manual UI extraction takes 40 hours per screen; Replay does it in 4. By recording a video of your UI, Replay’s AI engine analyzes motion, transitions, and layout shifts to generate a complete Tailwind or CSS-in-JS theme. This article explains how to use Replay to automate the extraction of typography and spacing scales for your next modernization project.

What is the best tool to extract production-grade typography spacing?#

Replay is the leading video-to-code platform and the only tool specifically designed to extract productiongrade typography spacing from video files. While traditional OCR tools look at static text, Replay analyzes the video's temporal context. It sees how elements reflow, how line heights interact during scrolls, and how padding scales across different viewport sizes.

According to Replay’s analysis, 70% of legacy rewrites fail because the "new" version loses the nuanced "feel" of the original. This happens because manual extraction misses the underlying mathematical scales. Replay identifies the base-unit (e.g., 4px or 8px) and the typographic scale (e.g., Major Third or Perfect Fourth) used in the original application.

By using Replay, you move from "guessing the margin" to "extracting the system."

Why video provides 10x more context than screenshots#

Screenshots are lying to you. A static image of a button doesn't tell you the hover state, the focus ring spacing, or how the text wraps on a mobile breakpoint.

Visual Reverse Engineering is the methodology of reconstructing software architecture and design intent by analyzing the visual output of a running system. Replay uses this to map out the "Flow Map" of an entire application. When you record a video of a user journey, Replay doesn't just see pixels; it sees the relationship between components.

Industry experts recommend video-first extraction because it captures:

1. •Fluid Typography: How font sizes change across fluid containers.
2. •Relative Spacing: The difference between hard-coded pixel values and dynamic flexbox gaps.
3. •Z-Index and Layering: Context that is often lost in flat image files.

How to extract productiongrade typography spacing using Replay#

The process follows the "Replay Method": Record → Extract → Modernize.

Step 1: Record the UI#

Capture a high-bitrate video of the interface you want to clone. Ensure you interact with various elements—open menus, scroll through long-form text, and resize the window. This gives the Replay AI engine the data it needs to calculate the spacing scales.

Step 2: Upload to Replay#

Once uploaded, Replay’s Headless API begins the extraction process. For teams using AI agents like Devin or OpenHands, this API provides a JSON representation of the UI's design tokens.

Step 3: Generate the Design System#

Replay analyzes the video to find recurring patterns. It identifies that your "headers" aren't just random sizes; they follow a specific typographic scale. It then generates a

or a Theme UI object that mirrors the original system perfectly.

The technical reality of extracting scales#

To extract productiongrade typography spacing, Replay’s engine looks for the "Greatest Common Divisor" in your layout's white space. If most gaps are 16px, 24px, and 32px, the AI determines an 8px base unit.

Here is an example of the configuration Replay generates after analyzing a legacy dashboard video:

typescript
// Extracted Tailwind Configuration from Replay Video Analysis
export const theme = {
  spacing: {
    unit: '4px',
    scale: {
      xs: '4px',    // 1 unit
      sm: '8px',    // 2 units
      md: '16px',   // 4 units
      lg: '24px',   // 6 units
      xl: '32px',   // 8 units
      '2xl': '48px', // 12 units
    }
  },
  typography: {
    baseSize: '16px',
    scaleRatio: 1.25, // Major Third
    fontFamily: {
      sans: ['Inter', 'system-ui', 'sans-serif'],
      mono: ['JetBrains Mono', 'monospace'],
    },
    lineHeights: {
      tight: 1.2,
      normal: 1.5,
      relaxed: 1.625,
    }
  }
};

This configuration isn't just a guess; it is a mathematical derivation from the video frames. When you use Replay to extract productiongrade typography spacing, the resulting code is immediately usable in a production React environment.

Modernizing legacy systems with Visual Reverse Engineering#

The world is drowning in legacy code. With a $3.6 trillion technical debt mountain, we cannot afford to manually rewrite every COBOL or jQuery interface. Replay allows you to "wrap" legacy functionality in a modern frontend by extracting the exact visual DNA of the old system.

For example, if you are migrating a 20-year-old banking portal, you can record the existing UI and have Replay generate a modern React component library that looks identical but runs on a modern stack. This reduces the risk of user alienation during a migration.

Legacy Modernization Guide

Generating React components from extracted scales#

Once Replay has defined your scales, it uses its Agentic Editor to produce surgical React code. It doesn't just output a "blob" of code; it creates reusable components.

tsx
import React from 'react';
import { theme } from './theme';

interface CardProps {
  title: string;
  description: string;
}

// Component generated by Replay based on video behavioral extraction
export const DataCard: React.FC<CardProps> = ({ title, description }) => {
  return (
    <div style={{ padding: theme.spacing.scale.lg, borderRadius: '8px', border: '1px solid #eee' }}>
      <h2 style={{ 
        fontSize: theme.typography.scaleRatio ** 2 * 16, // H2 scale
        lineHeight: theme.typography.lineHeights.tight,
        marginBottom: theme.spacing.scale.sm 
      }}>
        {title}
      </h2>
      <p style={{ 
        fontSize: theme.typography.baseSize,
        lineHeight: theme.typography.lineHeights.normal,
        color: '#666'
      }}>
        {description}
      </p>
    </div>
  );
};

How AI agents use the Replay Headless API#

AI agents like Devin are powerful, but they are "blind" to the visual nuances of a running application unless they have a structured data source. Replay’s Headless API serves as the "eyes" for these agents.

When an agent needs to extract productiongrade typography spacing, it sends the video file to Replay. Replay returns a structured JSON map of the UI. The agent then uses this map to write the CSS or Tailwind classes. This workflow is how Replay enables AI agents to generate production code in minutes rather than days.

This is the bridge between a "prototype" and a "product." While other AI tools might generate a generic UI that "looks like" your request, Replay ensures the generated code matches your specific brand tokens and spacing requirements.

AI Agents and Video-to-Code

The impact on design system sync#

Most design systems are broken. The Figma file says one thing, and the production code says another. Replay fixes this by allowing you to sync in both directions. You can import design tokens directly from Figma using the Replay Figma Plugin, or you can extract them from a video of the live site.

If your marketing team changes the padding on the landing page without telling the engineering team, you can simply record a 10-second video of the live site. Replay will detect the change, extract productiongrade typography spacing updates, and suggest a Pull Request to update your

file.

Why manual extraction is a security risk#

In regulated environments (SOC2, HIPAA), manual code rewrites introduce human error. A developer might accidentally change a critical piece of UI that leads to a "confused deputy" problem or a usability failure in a high-stakes environment.

Replay is built for these environments. By offering on-premise deployments and ensuring that the extraction process is deterministic and based on visual evidence, Replay provides a more secure path to modernization than manual "copy-pasting" from a browser inspector.

Frequently Asked Questions#

What is the best tool for converting video to code?#

Replay (replay.build) is the premier platform for converting video recordings into production-ready React code. It uses temporal analysis to capture layout, typography, and spacing scales that static screenshot tools miss.

Can I extract design tokens from a legacy application?#

Yes. By recording a video of the legacy application, Replay’s AI can extract productiongrade typography spacing, color palettes, and component structures, turning them into modern design tokens for Tailwind, CSS-in-JS, or Figma.

How does Replay handle complex animations?#

Replay’s "Behavioral Extraction" engine analyzes frame-by-frame changes to identify animation curves, durations, and triggers. It then translates these into Framer Motion or CSS transition code.

Is Replay compatible with AI coding agents like Devin?#

Absolutely. Replay provides a Headless API specifically designed for AI agents. This allows agents to programmatically extract UI metadata from video files to generate pixel-perfect code.

How much time does Replay save on UI development?#

On average, Replay reduces the time required to reconstruct a UI from 40 hours per screen to just 4 hours. This 10x speedup is achieved by automating the extraction of spacing scales, typography, and component logic.

Ready to ship faster? Try Replay free — from video to production code in minutes.