apply colors to light and dark mode comment area

src/client/styles/scss/theme/_apply-colors-dark.scss

@@ -363,3 +363,12 @@ body.on-edit {
     }
   }
 }
+
+/*
+ * GROWI comment form
+ */
+.growi .main {
+  .page-comments-row {
+    background: $gray-900;
+  }
+}

src/client/styles/scss/theme/_apply-colors-light.scss

@@ -293,3 +293,12 @@ $table-hover-bg: $bgcolor-table-hover;
     }
   }
 }
+
+/*
+ * GROWI comment form
+ */
+.growi .main {
+  .page-comments-row {
+    background: $gray-100;
+  }
+}

src/client/styles/scss/theme/_apply-colors.scss

@@ -452,16 +452,12 @@ body.on-edit {
  * GROWI comment form
  */
 .growi .main {
-  .page-comments-row {
-    border-top-color: $border-color-theme;
-  }
-
   .page-comment .page-comment-main,
   .page-comment-form .comment-form-main {
-    background-color: darken($bgcolor-global, 4%);
+    background-color: $bgcolor-global;
 
     &:before {
-      border-right-color: darken($bgcolor-global, 4%);
+      border-right-color: $bgcolor-global;
     }
 
     .nav.nav-tabs {