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Tweaking Reader View for better sepia background

  • I have long wanted to change the "sepia" colour in Reader View (Version 2) by bernarpa - the reader that is a porting of Firefox Reader View.

    The provided colour for "sepia" is far too bright. Details of how I did this on a PC running Windows 10 Pro are below.

    But it should not have worked! Any change to an extension (other than by updating it) should result in the change being detected and the extension being disabled. This does not happen with this extension, possibly because it is now pretty old.

    Note: the extension folder name is possibly random (in my case gfaafookaidboehhnhojbebjpjbnnfg) but you can identify the correct one by the sub folder name which is the version (in this case 2_0) and by the contents therein.

    Replace the HTM color code #FFFAFD with #e7d9c3 or with any color code you like in the following two files.

    For color examples, see or

    content.js located in:

    C:\Users{your user name}\AppData\Roaming\Opera Software\Opera Stable\Extensions/gfaafookaidboehhnhojbebjpjbnnfgl/2_0/js

    search for the phrase color === 'sepia’

    html += " } else if (color === 'sepia') {"
    html += " = '#e7d9c3';";

    aboutReaderControls.css located in:

    C:\Users{your user name}\AppData\Roaming\Opera Software\Opera Stable\Extensions/gfaafookaidboehhnhojbebjpjbnnfgl/2_0/css

    search for the text “sepia-button”

    .sepia-button {
    color: black;
    background-color: #e7d9c3;

    I was also able to make these changes on a Mac running OSX 10.13.4 but on another also running 10.13.4 the changes were detected and the addon was automatically disabled.