High Contrast Mode Forcer

WHAT IT DOES

This script forces high contrast themes on any webpage, making text easier to read for people with low vision, visual impairments, or anyone who prefers high contrast. When enabled, the script applies CSS filters and color overrides to invert colors, adjust brightness, and enhance contrast. You can choose from five high contrast themes: Dark (black background, white text), Light (white background, black text), Yellow on Black, Black on White (ultra-high contrast), and Sepia (warm, high contrast). A toggle lets you enable or disable the mode instantly. An option to preserve images lets you apply contrast only to text while keeping images unchanged. The selected theme is saved locally and persists across browsing sessions.

WHERE IT RUNS

The script runs on all websites (*://*/*), making it truly universal. It works on any page with visual content—articles, documents, emails, social media, dashboards, and more. It supports both desktop and mobile views.

HOW TO USE

After installation, the settings panel appears on the left side of the screen with the gear emoji (⚙️). Open the panel to configure the script:

- The "Enable high contrast mode" toggle enables or disables the script.

- Select a theme from the buttons: "Dark," "Light," "Yellow on Black," "Black on White," or "Sepia."

- Toggle "Preserve images" to keep images unchanged while applying contrast to text.

- Click "Refresh" to re-apply the theme if it doesn't appear correctly.

- Click "Reset" to restore the default settings.

The high contrast mode applies instantly when enabled. The theme is saved automatically.

TECHNICAL SECTION — REAL MECHANISM

The script injects a style element into the page head containing CSS rules that override the page's default colors and apply filters. The themes are implemented using a combination of CSS filters (invert, hue-rotate, contrast, brightness, sepia, saturate) and color overrides. The "Dark" theme uses invert(1) hue-rotate(180deg) to invert all colors, then adds contrast(1.2) for enhanced readability. The "Light" theme uses contrast(1.5) brightness(1.1) to increase contrast without color inversion. The "Yellow on Black" theme combines inversion with color adjustments to achieve yellow text on a black background. The "Black on White" theme uses contrast(2) brightness(1.2) for ultra-high contrast. The "Sepia" theme uses sepia(1) contrast(1.4) for a warm, high-contrast look. The preserve images option adds an override that sets filter: none !important on img, video, canvas, and iframe elements. The style element is recreated whenever the theme changes, and a MutationObserver watches for DOM changes to re-apply the theme when new content is loaded.

THE PANEL

The settings panel is built with BotGentz's BGPanel component. It is draggable via its header, allowing you to reposition it anywhere on the screen. The panel snaps to the left edge by default but can be moved freely. Click the gear emoji to collapse the panel into a small bubble, and click the bubble to expand it again. The panel remembers its position per page session. Press the Escape key to quickly close or minimize the panel. The panel includes a status flash bar that provides visual feedback when settings are changed or actions are performed. All settings save automatically via GM_setValue.

PLEASE NOTE

This script requires the free BotGentz browser extension to run. It does not function as a standalone Chrome extension and does not use chrome.* APIs. The script applies filters to the entire page, which may affect the appearance of images, videos, and UI elements. The "Preserve images" option helps mitigate this. Some websites may use custom styles that conflict with the high contrast overrides. The script uses CSS !important to override site styles, which may cause issues on sites with complex styling. The script stores only your preferences via GM_setValue. No data is sent externally—all data is stored locally in your browser. The script never reads or writes password fields, hidden inputs, or file inputs. All DOM operations use safe methods (style properties, textContent, appendChild) and never use innerHTML.