refactor: improve colors to better handle WCAG standards

Author: mrholek

scss/_variables-dark.scss

@@ -43,7 +43,7 @@ $disabled-dark:         rgba($white, .38) !default; // Deprecated in v5.0.0
 
 // scss-docs-start theme-color-dark-variables
 $primary-dark:       desaturate($primary, 10%) !default;
-$secondary-dark:     desaturate($secondary, 10%) !default;
+$secondary-dark:     $secondary !default;
 $success-dark:       desaturate($success, 10%) !default;
 $info-dark:          desaturate($info, 10%) !default;
 $warning-dark:       desaturate($warning, 10%) !default;
@@ -67,7 +67,7 @@ $theme-colors-dark: (
 
 // scss-docs-start theme-text-dark-variables
 $primary-text-emphasis-dark:        desaturate($primary-text-emphasis, 10%) !default;
-$secondary-text-emphasis-dark:      desaturate($secondary-text-emphasis, 10%) !default;
+$secondary-text-emphasis-dark:      $secondary-text-emphasis !default;
 $success-text-emphasis-dark:        desaturate($success-text-emphasis, 10%) !default;
 $info-text-emphasis-dark:           desaturate($info-text-emphasis, 10%) !default;
 $warning-text-emphasis-dark:        desaturate($warning-text-emphasis, 10%) !default;

scss/_variables.scss

@@ -311,7 +311,7 @@ $cyans: (
 // scss-docs-start theme-color-variables
 $primary:       #5856d6 !default;
 $secondary:     #6b7785 !default;
-$success:       #1b9e3E !default;
+$success:       #1b9e3e !default;
 $info:          #39f !default;
 $warning:       #f9b115 !default;
 $danger:        #e55353 !default;