Site Colors Not Working Correctly

According the theme documentation, in the section titled "How to use the w3css predefined themes" it says the following:

"Go to your-drupal-site-name/admin/appearance/settings/drupal8_w3css_theme and click on w3css predefined themes to expand it. Copy and paste any of your desired w3css color theme and click save. FYI: if you have any w3 classes in Advanced Site Color Section they will override the uploaded color theme."

Notice that last sentence. That does not appear to be correct - or else the theme is not working as the designers thought it does.

Below are the steps I took to test it out.

1) Start with the color defaults and logo as provided by the theme
2) In Firefox, open a New Private Window
3) Open my basic website and verify that the color theme is the default black and shades of grey throughout
4) Close that Private Window

5) Go to Appearance -> Settings -> Drupal 8 W3CSS Theme
6) In the "W3CSS Predefined Themes" section enter: w3-theme-indigo
7) Click "Save configuration"
8) Go to Configuration -> Development - > Performance and "Clear all caches" (just to be extra safe that no old information could be interfering with my results)

9) In Firefox, open a New Private Window
10) Open my basic website
11) Verify that all colors in the site are various shades of blue
12) Close that Private Window

13) Go to Appearance -> Settings -> Drupal 8 W3CSS Theme
14) In the "Advance Site Colors" section, in the "Enter Header Background color, Text Color or any W3.CSS classes" field enter: w3-red
15) Click "Save configuration"
16) Go to Configuration -> Development - > Performance and "Clear all caches"

17) In Firefox, open a New Private Window
18) Open my basic website
19) Note that all colors in the site are still various shades of blue - but the header area is NOT red
20) Close that Private Window

21) Go to Appearance -> Settings -> Drupal 8 W3CSS Theme
22) In the "W3CSS Predefined Themes" section clear that field
23) Click "Save configuration"
24) Go to Configuration -> Development - > Performance and "Clear all caches"

25) In Firefox, open a New Private Window
26) Open my basic website
27) Note that the header is now red, and all of the other colors are the default black and shades of grey throughout
28) Close that Private Window

29) Let's double-check with a different predefined theme. Go to Appearance -> Settings -> Drupal 8 W3CSS Theme
30) In the "W3CSS Predefined Themes" section enter: w3-theme-green
31) Click "Save configuration"
32) Go to Configuration -> Development - > Performance and "Clear all caches"

33) In Firefox, open a New Private Window
34) Open my basic website
35) Note that all colors in the site are various shades of green - and the header area is again NOT red
36) Close that Private Window

In case any of the modules I installed are causing the above problems, here are what I have installed and enabled so far. In each line is the name of the module, followed by the Extend Section and Checkboxes that were enabled.

CTools - Chaos tool suite / Chaos tools
Token - Other / Token

AddToAny - Other / AddToAny
Admin Toolbar - Administration / Admin Toolbar and Admin Toolbar Extra Tools
Display Suite - Display Suite / Display Suite + Core Experimental / Layout Discovery
Google Analytics - Statistics / Google Analytics
Meta tag - SEO / Metatag
Pathauto - Other / Pathauto
Sitemap - Other / Sitemap

And CKEditor enhancements:

Panel button
Color button
Font size and family