Adjust rich text editor background color

customize.dist/src/less2/include/colortheme-dark.less

@@ -51,6 +51,7 @@
 @cryptpad_color_grey_600: #757575;
 @cryptpad_color_grey_700: #616161;
 @cryptpad_color_grey_800: #424242;
+@cryptpad_color_grey_850: #323232;
 @cryptpad_color_grey_900: #212121;
 @cryptpad_color_grey_950: #121212;
 @cryptpad_color_black: #000;

customize.dist/src/less2/include/colortheme.less

@@ -51,6 +51,7 @@
 @cryptpad_color_grey_600: #757575;
 @cryptpad_color_grey_700: #616161;
 @cryptpad_color_grey_800: #424242;
+@cryptpad_color_grey_850: #323232;
 @cryptpad_color_grey_900: #212121;
 @cryptpad_color_grey_950: #121212;
 @cryptpad_color_black: #000;

www/pad/inner.js

@@ -1220,8 +1220,8 @@ define([
                 var $iframe = $('iframe').contents();
                 if (window.CryptPad_theme === 'dark') {
                     $iframe.find('html').addClass('cp-dark').css({
-                        'background-color': '#222', // XXX make sure it's the same in www/pad/app-pad.less
-                        'color': '#aaa' // XXX
+                        'background-color': '#323232', // grey_850
+                        'color': '#EEEEEE' // dark text_col
                     });
                 } else {
                     $iframe.find('html').css({