diff --git a/src/compatibility/_os.scss b/src/compatibility/_os.scss
index 9fa7c5e..52ee851 100644
--- a/src/compatibility/_os.scss
+++ b/src/compatibility/_os.scss
@@ -24,10 +24,14 @@
   }
 }
 
+//-- Mixin ---------------------------------------------------------------------
 @mixin _os_winTabBarTextColor {
   /* background textcolor */
   color: var(--lwt-text-color) !important;
 }
+
+//------------------------------------------------------------------------------
+
 @include OS($win7) {
   #TabsToolbar {
     &:-moz-lwtheme {
@@ -81,6 +85,7 @@
   }
 }
 
+//-- Mixin ---------------------------------------------------------------------
 @mixin _os_menuEmulate($bgRate, $bdRate) {
   menu[_moz-menuactive="true"],
   menuitem[_moz-menuactive="true"] {
@@ -93,6 +98,9 @@
     }
   }
 }
+
+//------------------------------------------------------------------------------
+
 @include OS($win7) {
   @include _os_menuEmulate(5%, 60%);
 
@@ -140,6 +148,7 @@
 }
 
 /*= Linux - Light System Default Theme's Selected Tab ========================*/
+//-- Mixin ---------------------------------------------------------------------
 $_os_linuxDefaultShadow: 0 0 4px rgba(128, 128, 142, 0.5);
 @mixin _os_linuxDefaultThemeSelectedTab {
   #tabbrowser-tabs:not([noshadowfortests])
@@ -149,6 +158,9 @@ $_os_linuxDefaultShadow: 0 0 4px rgba(128, 128, 142, 0.5);
     @content;
   }
 }
+
+//------------------------------------------------------------------------------
+
 @include OS($linux) {
   @include Light {
     /* Because of
diff --git a/src/decoration/_animate.scss b/src/decoration/_animate.scss
index 8c7035a..25997a7 100644
--- a/src/decoration/_animate.scss
+++ b/src/decoration/_animate.scss
@@ -1,4 +1,5 @@
 /*- Background Color -------------------------------------------------------*/
+//-- Mixin ---------------------------------------------------------------------
 @mixin _animate_bgColor($duration, $presudo: "") {
   button#{$presudo},
   toolbarbutton#{$presudo},
@@ -9,6 +10,9 @@
     transition: background-color $duration var(--animation-easing-function) !important;
   }
 }
+
+//------------------------------------------------------------------------------
+
 @include _animate_bgColor(1s);
 @include _animate_bgColor(0.25s, ":hover");
 @include OS($linux) {
diff --git a/src/library/_contents_menu.scss b/src/library/_contents_menu.scss
index 74c7f22..a11e506 100644
--- a/src/library/_contents_menu.scss
+++ b/src/library/_contents_menu.scss
@@ -4,6 +4,7 @@ menupopup menu:not([type="checkbox"], [type="radio"]),
   -moz-appearance: none !important; /* Linux: menulist */
 }
 
+//-- Mixin ---------------------------------------------------------------------
 @function _library_iconTargetSelector($target: "menu") {
   // .menu-iconic, .menuitem-iconic: Alreay exist, not target.
   // .in-menulist: Not a range because it is a select menu of web content.
@@ -32,6 +33,8 @@ $_library_menuSelector: _library_iconTargetSelector("menu");
   }
 }
 
+//------------------------------------------------------------------------------
+
 @include _library_contextMenu {
   /* Color */
   -moz-context-properties: fill, fill-opacity !important;
diff --git a/src/padding/_drag_space.scss b/src/padding/_drag_space.scss
index 7602622..2cfa38e 100644
--- a/src/padding/_drag_space.scss
+++ b/src/padding/_drag_space.scss
@@ -4,7 +4,8 @@
   --space-above-tabbar: 8px; /* If the option is not specified, it is equivalent to 0px. */
 }
 
-@mixin dragSpaceHeight {
+//-- Mixin ---------------------------------------------------------------------
+@mixin _dragSpaceHeight {
   :root[tabsintitlebar][sizemode="normal"] #toolbar-menubar[autohide="true"] {
     @content;
   }
@@ -14,7 +15,7 @@
     }
   }
 }
-@mixin dragSpacePadding {
+@mixin _dragSpacePadding {
   /* Add extra space to titlebar for dragging */
   :root[sizemode="normal"][chromehidden~="menubar"] #TabsToolbar > .toolbar-items,
   :root[sizemode="normal"] #toolbar-menubar[autohide="true"][inactive] + #TabsToolbar > .toolbar-items {
@@ -28,13 +29,15 @@
   }
 }
 
+//------------------------------------------------------------------------------
+
 @include OS($win10) {
-  @include dragSpaceHeight {
+  @include _dragSpaceHeight {
     height: calc(var(--tab-min-height) + var(--space-above-tabbar) - var(--tabs-navbar-shadow-size));
   }
 }
 @include OS($win7, $win8, $linux) {
-  @include dragSpaceHeight {
+  @include _dragSpaceHeight {
     height: calc(var(--tab-min-height) + var(--space-above-tabbar));
   }
 }
@@ -46,12 +49,12 @@
 }
 @include OS($win7) {
   /* Add 4px extra margin on top of the tabs toolbar on Windows 7. */
-  @include dragSpacePadding {
+  @include _dragSpacePadding {
     padding-top: calc(var(--space-above-tabbar) + 4px) !important;
   }
 }
 @include OS($win8, $win10, $linux) {
-  @include dragSpacePadding {
+  @include _dragSpacePadding {
     padding-top: var(--space-above-tabbar) !important;
   }
 }
diff --git a/src/tabbar/clipped_tab/_pinned_close_button.scss b/src/tabbar/clipped_tab/_pinned_close_button.scss
index e5f2b1d..7f49852 100644
--- a/src/tabbar/clipped_tab/_pinned_close_button.scss
+++ b/src/tabbar/clipped_tab/_pinned_close_button.scss
@@ -8,6 +8,7 @@
   --uc-close-button-padding: 4px;
 }
 
+//-- Mixin ---------------------------------------------------------------------
 @mixin pinnedCloseButtonShow($prefix: "") {
   #{$prefix}:not([busy]) .tab-close-button {
     display: -moz-box !important;
@@ -33,6 +34,8 @@
   }
 }
 
+//------------------------------------------------------------------------------
+
 .tabbrowser-tab[pinned] {
   @include pinnedCloseButtonShow("&[visuallyselected]:not([style*='transform: translateX']):hover");
   @include pinnedIconStackLayout("&[visuallyselected]:not([style*='transform: translateX']):hover");
diff --git a/src/tabbar/unselected_tab/_dynamic_separator.scss b/src/tabbar/unselected_tab/_dynamic_separator.scss
index e80c7ef..9633b1b 100644
--- a/src/tabbar/unselected_tab/_dynamic_separator.scss
+++ b/src/tabbar/unselected_tab/_dynamic_separator.scss
@@ -1,4 +1,5 @@
-@mixin separatorShape() {
+//-- Mixin ---------------------------------------------------------------------
+@mixin _dynamicSeparatorShape() {
   /* Box Model */
   content: "";
   display: block;
@@ -20,6 +21,8 @@
   }
 }
 
+//------------------------------------------------------------------------------
+
 @include Option("userChrome.tab.newtab_button_like_tab") {
   #tabbrowser-arrowscrollbox {
     position: absolute;
@@ -27,7 +30,7 @@
 
   .tab-background::before,
   #tabs-newtab-button::before {
-    @include separatorShape;
+    @include _dynamicSeparatorShape;
 
     /* More position */
     transform: translateX(-2.5px) translateY(calc(-50% + 1px));
@@ -39,7 +42,7 @@
   #tabbrowser-arrowscrollbox:not([overflowing])
     .tabbrowser-tab:not([visuallyselected], [multiselected], :hover)[last-visible-tab]
     .tab-background::after {
-    @include separatorShape;
+    @include _dynamicSeparatorShape;
   }
 
   .tab-background::before {