ctrl-center

The ultimate, production-ready solution for centering divs across all frameworks and browsers.

Finally, an npm package that solves the hardest problem in CSS: centering a div. But this isn't just another meme package—this is a comprehensive, enterprise-grade solution with framework support, accessibility features, and extensive testing.

✨ Features

• 🎯 Multiple centering methods - Grid, Flexbox, Absolute, Text, and more
• 🌐 Framework agnostic - Works with React, Vue, Angular, and vanilla HTML
• 📱 Responsive design - Container queries and viewport-aware centering
• ♿ Accessibility first - WCAG compliant with reduced motion support
• 🌍 RTL support - Full right-to-left language compatibility
• ⚡ Performance optimized - GPU acceleration and containment optimizations
• 🔧 Developer friendly - TypeScript definitions and comprehensive tooling
• 🛡️ Production ready - Extensive testing and conflict detection

🚀 Quick Start

Installation

# npm
npm install ctrl-center

# yarn
yarn add ctrl-center

# pnpm
pnpm add ctrl-center

🎬 Demos

Try the package as an npm dependency via local demos powered by Vite.

React (Vite)

cd demo/react
npm install
npm run dev

Then open the printed local URL (default http://localhost:5173).

Vue 3 (Vite)

cd demo/vue
npm install
npm run dev

Then open the printed local URL (default http://localhost:5174).

Both demos consume this package via a local file dependency (see demo/react/package.json and demo/vue/package.json), importing ctrl-center/center.css and the framework bindings (ctrl-center/react, ctrl-center/vue).

Angular (Vite + Analog)

cd demo/angular
npm install
npm run dev

Then open the printed local URL (default http://localhost:5175).

Tailwind (Vite)

cd demo/tailwind
npm install
npm run dev

Then open the printed local URL (default http://localhost:5176).

CSS-in-JS (React + styled-components/emotion)

cd demo/css-in-js
npm install
npm run dev

Then open the printed local URL (default http://localhost:5177).

Next.js (SSR)

cd demo/next
npm install
npm run dev

Then open http://localhost:3000.

CDN (no build step)

• Open demo/cdn.html directly in your browser, or serve the repo root:

npx serve .
# then navigate to /demo/cdn.html

Basic Usage

<!-- Import the CSS -->
<link rel="stylesheet" href="node_modules/ctrl-center/center.css">

<!-- Center a div using CSS Grid (recommended) -->
<div class="center-div">
  <div>I'm perfectly centered!</div>
</div>

<!-- Or use Flexbox -->
<div class="center-flex">
  <div>Also perfectly centered!</div>
</div>

// ES modules
import 'ctrl-center/center.css';

// CommonJS
require('ctrl-center/center.css');

📚 Centering Methods

Primary Methods

| Class | Method | Use Case | Browser Support | |-------|--------|----------|----------------| | center-div | CSS Grid | Modern default | IE11+ (with fallback) | | center-flex | Flexbox | Legacy support | IE11+ | | center-x | Horizontal only | Single axis | IE11+ | | center-y | Vertical only | Single axis | IE11+ |

Specialized Methods

| Class | Description | Use Case | |-------|-------------|----------| | absolute-center | Absolute positioning | Overlays, modals | | viewport-center | Full viewport height | Landing pages | | fullscreen-center | Fixed fullscreen | Splash screens | | text-center | Text alignment | Typography | | inline-center | Inline elements | Buttons, badges |

Responsive Centering

<!-- Automatically switches between flex and grid based on container size -->
<div class="center-responsive">
  <div>Smart responsive centering!</div>
</div>

🎨 Customization

CSS Custom Properties

.my-container {
  --center-gap: 20px;           /* Space between items */
  --center-padding: 30px;       /* Container padding */
  --center-max-width: 500px;    /* Constrain child width */
  --center-max-height: 300px;   /* Constrain child height */
}

Example with Custom Properties

<div class="center-div" style="--center-gap: 1rem; --center-padding: 2rem;">
  <div>Item 1</div>
  <div>Item 2</div>
  <div>Item 3</div>
</div>

⚛️ Framework Integration

React

import { CenterDiv, useCenterDiv } from 'ctrl-center/react';

// Component approach
function App() {
  return (
    <CenterDiv gap="1rem" padding="2rem">
      <div>Centered content</div>
    </CenterDiv>
  );
}

// Hook approach
function MyComponent() {
  const centerRef = useCenterDiv({ method: 'flex', responsive: true });
  
  return (
    <div ref={centerRef}>
      <div>Content</div>
    </div>
  );
}

// Higher-order component
const CenteredComponent = withCenterDiv(MyComponent, { method: 'grid' });

Vue 3

<template>
  <CenterDiv :gap="16" :responsive="true">
    <div>Centered content</div>
  </CenterDiv>
</template>

<script setup>
import { CenterDiv, useCenterDiv } from 'ctrl-center/vue';

// Composition API
const { centerClass, updateOptions } = useCenterDiv({
  method: 'flex',
  gap: '1rem'
});
</script>

Angular

// Component
import { CenterDivComponent } from 'ctrl-center/angular';

@Component({
  template: `
    <center-div [gap]="'1rem'" [method]="'grid'">
      <div>Centered content</div>
    </center-div>
  `
})
export class MyComponent {}

// Directive
@Component({
  template: `
    <div centerDiv [centerMethod]="'flex'" [centerGap]="'1rem'">
      <div>Content</div>
    </div>
  `
})
export class MyComponent {}

CSS-in-JS

import { createCenterStyles } from 'ctrl-center/css-in-js';

const styles = createCenterStyles({
  method: 'grid',
  gap: '1rem',
  padding: '2rem',
  responsive: true
});

// Usage with styled-components
const CenteredDiv = styled.div`
  ${styles}
`;

// Usage with emotion
const CenteredDiv = styled.div(styles);

Tailwind CSS

// tailwind.config.js
module.exports = {
  plugins: [
    require('ctrl-center/tailwind')
  ]
}

<!-- Use the generated utilities -->
<div class="center-grid gap-4 p-8">
  <div>Centered with Tailwind!</div>
</div>

♿ Accessibility Features

Built-in Accessibility

• Focus management: Proper focus outline and keyboard navigation
• High contrast: Automatic border in high contrast mode
• Reduced motion: Respects prefers-reduced-motion
• RTL support: Full right-to-left language support
• Screen readers: Semantic structure preservation

WCAG Compliance

<!-- Proper focus indicators -->
<div class="center-div" tabindex="0" role="main">
  <div>Accessible centered content</div>
</div>

<!-- RTL support -->
<div class="center-flex" dir="rtl">
  <div>المحتوى المتمركز</div>
</div>

🔧 Guardrails & Conflict Detection

Automatic Conflict Detection

import { CenterDivGuardrails } from 'ctrl-center/guardrails';

// Start guardrails (conflict detection, a11y checks, optional perf tracking)
const guardrails = new CenterDivGuardrails({
  logLevel: 'warn',            // 'none' | 'warn' | 'error'
  performanceTracking: true,   // enable paint/layout shift tracking
  a11yChecks: true,            // enable accessibility checks
  namespace: 'Demo'            // optional console prefix
});

// Get a consolidated report at any time
console.log(guardrails.getReport());

Framework Compatibility

The package automatically detects and works with:

• ✅ Bootstrap - Graceful coexistence with Bootstrap utilities
• ✅ Tailwind CSS - Complementary utility classes
• ✅ Foundation - Compatible with Foundation grid
• ✅ Bulma - Works alongside Bulma flexbox utilities
• ✅ Custom CSS - Non-destructive integration

📱 Browser Support

| Browser | Support | Notes | |---------|---------|-------| | Chrome | 88+ | Full support | | Firefox | 87+ | Full support | | Safari | 14+ | Full support | | Edge | 88+ | Full support | | IE11 | Partial | Flexbox fallback |

Progressive Enhancement

/* Modern browsers get Grid */
.center-div {
  display: grid;
  place-items: center;
}

/* IE11 gets Flexbox fallback */
@supports not (display: grid) {
  .center-div {
    display: flex;
    justify-content: center;
    align-items: center;
  }
}

⚡ Performance

Bundle Size

• Core CSS: 4.2KB minified, 1.1KB gzipped
• React components: +2.1KB
• Vue components: +1.8KB
• Angular components: +3.2KB

Performance Optimizations

• CSS containment for layout isolation
• GPU acceleration for transforms
• Layer hints for browser optimization
• Container queries for efficient responsive design

Performance Monitoring

import { CenterDivGuardrails } from 'ctrl-center/guardrails';

const guardrails = new CenterDivGuardrails({ performanceTracking: true });

// Later, read performance metrics collected so far
const { performance } = guardrails.getReport();
console.table(performance.paintTimes);
console.table(performance.layoutShifts);

🧪 Testing

Running Tests

# Run all tests
npm test

# Run specific test suites
npm run test:unit
npm run test:browser
npm run test:accessibility

# Run with coverage
npm run test:coverage

Test Coverage

• ✅ 43/43 tests passing (100% coverage)
• ✅ Cross-browser compatibility
• ✅ Accessibility compliance
• ✅ Performance benchmarks
• ✅ Framework integration

Writing Your Own Tests

import { assertCentered } from 'ctrl-center/test-helpers';

test('my component is centered', async ({ page }) => {
  await page.setContent(`
    <div class="container center-div">
      <div class="content">Hello</div>
    </div>
  `);
  
  await assertCentered(page, '.content', '.container');
});

🔄 Migration Guide

From Custom CSS

/* Before */
.my-center {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

/* After */
.my-center {
  @apply center-div; /* With Tailwind */
  /* OR */
  /* Remove custom CSS and use class="center-div viewport-center" */
}

From Other Libraries

// From react-center
// Before
import Center from 'react-center';
<Center><div>Content</div></Center>

// After
import { CenterDiv } from 'center-div/react';
<CenterDiv><div>Content</div></CenterDiv>

🛠️ Advanced Usage

Custom Centering Method

.my-custom-center {
  display: grid;
  grid-template-areas: ". . ." ". content ." ". . .";
  grid-template-columns: 1fr auto 1fr;
  grid-template-rows: 1fr auto 1fr;
}

.my-custom-center > * {
  grid-area: content;
}

Responsive Breakpoints

@container (max-width: 480px) {
  .center-responsive {
    --center-gap: 0.5rem;
    --center-padding: 1rem;
  }
}

@container (min-width: 1200px) {
  .center-responsive {
    --center-gap: 2rem;
    --center-padding: 3rem;
  }
}

Animation Support

.animated-center {
  transition: all 0.3s ease;
}

.animated-center:hover {
  --center-gap: 2rem;
  transform: scale(1.05);
}

🐛 Troubleshooting

Common Issues

Q: My content isn't centering properly

<!-- ❌ Wrong: Missing container dimensions -->
<div class="center-div">
  <div>Content</div>
</div>

<!-- ✅ Correct: Container has dimensions -->
<div class="center-div" style="height: 300px;">
  <div>Content</div>
</div>

Q: Multiple items aren't spacing correctly

/* ✅ Use custom properties for spacing */
.my-container {
  --center-gap: 1rem;
}

Q: Conflicts with my existing CSS

// Enable conflict detection and checks
import { CenterDivGuardrails } from 'ctrl-center/guardrails';
const guardrails = new CenterDivGuardrails({});

Debug Mode

import 'center-div/debug.css'; // Adds visual debugging outlines

🤝 Contributing

We welcome contributions! Please see CONTRIBUTING.md for guidelines.

Development Setup

git clone https://github.com/yourusername/center-div.git
cd center-div
npm install
npm run dev

Running Tests

npm test          # Run all tests
npm run test:watch # Watch mode
npm run test:coverage # Coverage report

📄 License

MIT License - see LICENSE for details.

🙏 Acknowledgments

• Inspired by the eternal struggle of centering divs

Remember: The hardest problem in computer science is now solved. You're welcome 🤝