Update CSS variables for theme consistency, optimize color definitions, and refine placeholder styles.

Author: mallowigi

assets/css/main.css

@@ -10,13 +10,10 @@ previous:
   url: '/docs/configuration/file-status-colors'
   title: File Status Colors
 next:
-  url: '/docs/configuration/accents'
-  title: Accents
+  url: '/docs/configuration/adaptive-theme'
+  title: Adaptive Theme
 ---
 
-This feature is available in the free plan.
-{:class='card-panel warn'}
-
 Customize the editor scrollbars from the Color Scheme.
 {:class='title'}