Universal Line Height Adjuster

WHAT IT DOES

Universal Line Height Adjuster gives you precise control over the vertical spacing between lines of text on every website you visit. Instead of being constrained by the line-height values chosen by web designers, you can adjust the leading to your preferred comfort level using a simple slider control. This is especially valuable for readers who find dense text difficult to scan, or for those who prefer more generous spacing to reduce visual crowding and improve reading flow. The extension applies the line-height consistently across all text elements—paragraphs, headings, lists, blockquotes, table cells, form inputs, and more—while preserving the original font size, color, weight, and other styling attributes. A live preview lets you see changes in real-time as you adjust the slider, and a single toggle switch instantly reverts to the original page design or reapplies your custom setting. All preferences are saved locally, so your preferred line-height follows you across browsing sessions.

WHERE IT RUNS

The extension works on every website you visit, including complex single-page applications, news portals, social media platforms, e-commerce stores, document viewers, and web-based productivity tools. It runs locally in your browser, processing each page's DOM in real-time without sending any data to external servers. The line-height adjustment applies immediately on page load and continues to work as you navigate, scroll, and interact with dynamic content. Whether you're reading articles, filling out forms, or browsing product listings, your preferred line-height remains consistent. The extension supports all major browsers and adapts to both desktop and mobile viewports seamlessly.

HOW TO USE

After installation, click the extension toolbar icon to open the Universal Line Height Adjuster panel. Use the slider to adjust the line-height value from 0.8 (very tight) to 3.0 (very spacious), with a default of 1.6. The current value is displayed in real-time as you slide. Click "Apply" to save the current setting as your global default. To test different values quickly, use the preset buttons (1.2, 1.4, 1.6, 1.8, 2.0, 2.4) located below the slider—these apply a temporary preview without saving, letting you evaluate readability at different spacings. Use the toggle switch at the bottom of the panel to enable or disable the line-height adjustment entirely, reverting to the original design with a single click. For per-site customization, click "Apply to This Site Only" to save a unique line-height value for the current domain, overriding your global choice. To revert a site to your global setting, click "Reset Site to Global."

THE ACTUAL MECHANISM — CSS INJECTION WITH SELECTIVE PROPERTY OVERRIDE

Unlike browser extensions that attempt to modify individual elements one by one through JavaScript iteration, Universal Line Height Adjuster uses a high-performance CSS injection strategy. When you apply a line-height, the script creates a style element in the document head containing a CSS rule with the `!important` declaration. The rule targets a comprehensive selector list of all text-containing elements: `p, div, span, h1-h6, li, td, th, label, button, input, textarea, select, blockquote, article, section, nav, header, footer, and many more`. The `line-height: [value] !important;` declaration overrides any inline styles or framework-generated CSS, ensuring the spacing applies correctly across all frameworks including React, Vue, Angular, and WordPress. The `!important` flag is critical because many modern CSS frameworks use high-specificity selectors that would otherwise resist modification. For dynamic content, the extension uses a MutationObserver that detects when new elements are added to the DOM and re-injects the style rules only when necessary, avoiding performance degradation. This pipeline ensures near-instant response with zero layout recalculation overhead, even on content-heavy pages with thousands of elements.

THE PANEL

The settings panel is a lightweight, draggable overlay that appears in the center of your screen. You can reposition it by clicking and dragging the title bar; release it near the screen edge and it will snap into place automatically. To collapse the panel into a compact title bar, click the minimize button, expanding it again with the same control. The panel is fully responsive, adapting to different screen resolutions with a minimum width of 300px and a maximum of 480px. Press the Escape key at any time to dismiss the panel without applying changes. All controls—the line-height slider, preset buttons, apply and reset actions, per-site settings, and the enable/disable toggle—are accessible within a clean, high-contrast interface that respects your system's color scheme.

PLEASE NOTE

This extension requires the free BotGentz companion extension to be installed and active, which provides the underlying filtering engine and cross-browser compatibility layer. Because websites frequently update their code structures and frameworks, certain complex web applications may occasionally require script updates to maintain full line-height adjustment functionality. The extension will automatically check for updates weekly and notify you when a new version is available. No personal data, browsing history, or page content is ever collected, stored, or transmitted. All line-height preferences are saved using the browser's local storage API and remain solely on your device. The extension does not inject ads, trackers, or analytics of any kind.