Evolution, the background of messages is always grey

Well I have answered my own question (again). To correct this frankly stupid behaviour by Evolution one needs to go to

~/.config/gtk-3.0/

Inside that folder there should be a file called gtk.css, if not create it.

Add these lines to the file:

/* Black on white for HTML messages in Evolution Reader/Composer */
EMailView WebKitWebView, EMailReader WebKitWebView {
    color: #000000;
    background-color: #ffffff;
}

That's it. Regardless of theme email backgrounds will now be white as oppose to grey.

Taken from this thread on Launchpad

On other distributions based on Debian above won't work (mainly because you will not have elementary). This below resolves problem.

Find in your home holder .config/gtk-3.0/gtk.css and add:

/* Black on white for HTML messages in Evolution Reader/Composer */
/* adjust colour to your liking */
EMailView WebKitWebView, EMailReader WebKitWebView {
    color: #000fff;
    background-color: #fff000;
}

/*****************************
 * FIX EVOLUTION BLACK EMAIL *
 *****************************/
GtkWindow {
     color: @theme_fg_color;
     background-color: @theme_bg_color;
 }
GtkPaned {
     color: @theme_fg_color;

    /* Evolution sets the background color of its mail window to the background
     * color of entries, but cannot handle background images. Setting the
     * background color here doesn't effect real entries, because
     * 'background-image' has precedence.
     */
     background-color: @theme_bg_color;
 }