Polylight by Darky
A extension to apply smooth rainbow text selection highlighting for every website with the option to let the user choose its own solid/static color in the same app.
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About this extension
Polylight
Hello and welcome to Polylight, Polylight is a multi browser extension that lets you have a rainbow text highlighting color effect, don't specially want a rainbow highlight ? Worry not, you have the choice between solid colors and the RGB mode, in the solid color mode you have 6 presets with a section made to let you customize the color as you want it to be.
This is the remnant put back together with a nice UI and refactoring of an old extension I had made once to customize my highlight color and to add a rainbow effect, I hope you enjoy using it just as much as I do.
Performance Warning
Because of how browsers handle text selection natively, there is no generic CSS way to animate highlighting without forcefully injecting and updating CSS pseudo-elements (
This is incredibly heavy for browser layout engines to handle and carries an inherent continuous CPU footprint while rainbow mode is enabled. I can't really do much about this natively without breaking the layout of the websites themselves, so it remains a known limitation of the RGB effect, but I did take all precautions to limit the impacts. (Also good to note that your result may change from mine as I'm using Firefox without hardware acceleration from what I know (meaning it doesn't use the GPU to be quicker), but maybe I'm wrong, and it'll always hammer the CPU, like any browser activity)
Features
Hello and welcome to Polylight, Polylight is a multi browser extension that lets you have a rainbow text highlighting color effect, don't specially want a rainbow highlight ? Worry not, you have the choice between solid colors and the RGB mode, in the solid color mode you have 6 presets with a section made to let you customize the color as you want it to be.
This is the remnant put back together with a nice UI and refactoring of an old extension I had made once to customize my highlight color and to add a rainbow effect, I hope you enjoy using it just as much as I do.
Performance Warning
Because of how browsers handle text selection natively, there is no generic CSS way to animate highlighting without forcefully injecting and updating CSS pseudo-elements (
::selection). To make the rainbow effect work, the extension rapidly rewrites a <style> block directly into the webpage's HTML multiple times a second. This is incredibly heavy for browser layout engines to handle and carries an inherent continuous CPU footprint while rainbow mode is enabled. I can't really do much about this natively without breaking the layout of the websites themselves, so it remains a known limitation of the RGB effect, but I did take all precautions to limit the impacts. (Also good to note that your result may change from mine as I'm using Firefox without hardware acceleration from what I know (meaning it doesn't use the GPU to be quicker), but maybe I'm wrong, and it'll always hammer the CPU, like any browser activity)
Features
- Smooth Rainbow Mode: Custom time based loop to keep color shifts stable across webpages.
- Solid Color Mode: Switch to a solid color and build your own custom preset library. The CPU impact drops to zero while in this mode because it only refreshes it once.
- Smart Contrast: Text dynamically snaps to white or black only if the highlight combination becomes unreadable based on WCAG AAA standards.
- Granular UI: Matte charcoal interface with granular sliders for speed, opacity, saturation, lightness, and because I prefer minimalism.
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Permissions and data
Required permissions:
- Access your data for all web sites
Data collection:
- The developer says this extension doesn't require data collection.
More information
- Add-on Links
- Version
- 3.0.0
- Size
- 75.98 kB
- Last updated
- 5 days ago (4 Apr 2026)
- Related Categories
- Licence
- MIT Licence
- Version History
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