How to invert colors in Safari pages on macbook?

Any extension for the browser? I only want to invert safari's colors, not of the entire system.

Switch to reader view and then you can use the text settings to the right of the search bar to invert colors:

From here

According to Apple, you can change the colors of its Safari Web browser by using Cascading Style Sheets (CSS). Many websites offer free CSS templates for download (see Resources for some examples). You must have a CSS saved onto your computer before you can change the colors or style of your Safari browser.

Read more : http://www.ehow.com/how_6527587_change-colors-safari-browser.html

Example:

For example, to override a website using colored text on a colored background and set it to black text on a white background, you could add these styles:

body {

 color:black !important;

 background:white !important;

 }

How to Add a Style Sheet using extensions

Or use a software project that does this, like Stylish