diff --git a/app/design/adminhtml/Magento/backend/Magento_Analytics/web/css/source/_module.less b/app/design/adminhtml/Magento/backend/Magento_Analytics/web/css/source/_module.less
index 6d21462d753ca..ca83a2289ee92 100644
--- a/app/design/adminhtml/Magento/backend/Magento_Analytics/web/css/source/_module.less
+++ b/app/design/adminhtml/Magento/backend/Magento_Analytics/web/css/source/_module.less
@@ -115,7 +115,7 @@
 }
 
 .advanced-reports-subscription-modal {
-    h1:first-of-type {
+    h1::first-of-type {
         background: url("Magento_Analytics::images/analytics-icon.svg") no-repeat;
         background-size: 55px 49.08px;
         padding: 1.5rem 0 2rem 7rem;
@@ -158,9 +158,7 @@
     margin-top: 1rem;
 }
 
-/**
- * @codingStandardsIgnoreStart
- */
+/* @codingStandardsIgnoreStart */
 #row_analytics_general_vertical {
     >td.config-vertical-label {
         >label.admin__field-label {
@@ -168,3 +166,4 @@
         }
     }
 }
+/* @codingStandardsIgnoreEnd */
diff --git a/app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/_menu.less b/app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/_menu.less
index 7486fa76078e9..cf41a5d6d7052 100644
--- a/app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/_menu.less
+++ b/app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/_menu.less
@@ -53,10 +53,6 @@
 //  Utilities
 //  ---------------------------------------------
 
-/**
- * @codingStandardsIgnoreStart
- */
-
 .admin__menu-link() {
     color: @menu-item__color;
     display: block;
@@ -161,9 +157,7 @@
 
         .logo-img {
             height: @menu-logo-img__height;
-            transition: -webkit-filter .2s linear,
-            filter .2s linear,
-            transform .1s linear;
+            transition: -webkit-filter .2s linear, filter .2s linear, transform .1s linear;
             width: @menu-logo-img__width;
         }
     }
diff --git a/app/design/adminhtml/Magento/backend/Magento_Rma/web/css/source/_module.less b/app/design/adminhtml/Magento/backend/Magento_Rma/web/css/source/_module.less
index 16c84047b529d..1a6b6d261f946 100644
--- a/app/design/adminhtml/Magento/backend/Magento_Rma/web/css/source/_module.less
+++ b/app/design/adminhtml/Magento/backend/Magento_Rma/web/css/source/_module.less
@@ -6,22 +6,19 @@
 .media-width(@extremum, @break) when (@extremum = 'min') and (@break = @screen__m) {
     .rma-request-details,
     .rma-wrapper .order-shipping-address {
-        float: left;
-        /**
-         * @codingStandardsIgnoreStart
-         */
+        /* @codingStandardsIgnoreStart */
         #mix-grid .width(6, 12);
-        //@codingStandardsIgnoreEnd
+        /* @codingStandardsIgnoreEnd */
+        float: left;
     }
 
     .rma-confirmation,
-    .rma-wrapper .order-return-address, .rma-wrapper .order-shipping-method {
-        float: right;
-        /**
-        * @codingStandardsIgnoreStart
-        */
+    .rma-wrapper .order-return-address,
+    .rma-wrapper .order-shipping-method {
+        /* @codingStandardsIgnoreStart */
         #mix-grid .width(6, 12);
-        //@codingStandardsIgnoreEnd
+        /* @codingStandardsIgnoreEnd */
+        float: right;
     }
 }
 
diff --git a/app/design/adminhtml/Magento/backend/Magento_Tax/web/css/source/_module.less b/app/design/adminhtml/Magento/backend/Magento_Tax/web/css/source/_module.less
index 1758b71817152..9d90dd5c3501e 100644
--- a/app/design/adminhtml/Magento/backend/Magento_Tax/web/css/source/_module.less
+++ b/app/design/adminhtml/Magento/backend/Magento_Tax/web/css/source/_module.less
@@ -3,9 +3,6 @@
 //  * See COPYING.txt for license details.
 //  */
 
-/**
- * @codingStandardsIgnoreStart
- */
 .block-footer .action-add {
     -webkit-appearance: none;
     &:extend(.action-default, button all);
@@ -40,4 +37,3 @@
         }
     }
 }
-//@codingStandardsIgnoreEnd
diff --git a/app/design/adminhtml/Magento/backend/Magento_Ui/web/css/source/module/_data-grid.less b/app/design/adminhtml/Magento/backend/Magento_Ui/web/css/source/module/_data-grid.less
index e8d6472ce0b4b..002e7b97e2d17 100644
--- a/app/design/adminhtml/Magento/backend/Magento_Ui/web/css/source/module/_data-grid.less
+++ b/app/design/adminhtml/Magento/backend/Magento_Ui/web/css/source/module/_data-grid.less
@@ -12,9 +12,6 @@
 //  _____________________________________________
 
 //  Data Grid Change Indicator
-/**
- * @codingStandardsIgnoreStart
- */
 @data-grid-row-changed__icon: @icon-edit__content;
 @data-grid-row-changed-tooltip__background: @color-white-fog2;
 
@@ -1088,7 +1085,7 @@ body._in-resize {
 
     //  Content Hierarchy specific
     .adminhtml-cms-hierarchy-index & {
-        .data-grid-actions-cell:first-child {
+        .data-grid-actions-cell::first-child {
             padding: 0;
         }
     }
diff --git a/app/design/adminhtml/Magento/backend/web/css/source/actions/_actions-dropdown.less b/app/design/adminhtml/Magento/backend/web/css/source/actions/_actions-dropdown.less
index d1fe33c4fe77d..9848b610cebe3 100644
--- a/app/design/adminhtml/Magento/backend/web/css/source/actions/_actions-dropdown.less
+++ b/app/design/adminhtml/Magento/backend/web/css/source/actions/_actions-dropdown.less
@@ -168,15 +168,12 @@
     width: auto;
     z-index: 1;
 
-    /**
-     * @codingStandardsIgnoreStart
-     */
     &:hover {
-        &:extend(.abs-form-control-pattern:hover);
+        &:extend(.abs-form-control-pattern::hover);
     }
 
     &._focus {
-        &:extend(.abs-form-control-pattern:focus);
+        &:extend(.abs-form-control-pattern::focus);
     }
 
     &._active {
@@ -261,7 +258,7 @@
 
     .selectmenu:hover & {
         &:before {
-            &:extend(.abs-form-control-pattern:hover);
+            &:extend(.abs-form-control-pattern::hover);
         }
     }
 
@@ -270,7 +267,7 @@
     }
 
     .selectmenu._focus &:before {
-        &:extend(.abs-form-control-pattern:focus);
+        &:extend(.abs-form-control-pattern::focus);
     }
 
     body._keyfocus &:focus {
@@ -355,7 +352,7 @@
     white-space: nowrap;
     z-index: 1;
 
-    li:last-child & {
+    li::last-child & {
         padding-right: .4rem;
     }
 
diff --git a/app/design/adminhtml/Magento/backend/web/css/source/actions/_actions-multiselect.less b/app/design/adminhtml/Magento/backend/web/css/source/actions/_actions-multiselect.less
index c3cbffe4e8c4f..231b3f01ac4cf 100644
--- a/app/design/adminhtml/Magento/backend/web/css/source/actions/_actions-multiselect.less
+++ b/app/design/adminhtml/Magento/backend/web/css/source/actions/_actions-multiselect.less
@@ -11,9 +11,6 @@
 //  Variables
 //  _____________________________________________
 
-/**
- * @codingStandardsIgnoreStart
- */
 @action-multiselect-menu-item__padding: 1rem;
 @action-multiselect-menu-item__hover__background-color: @color-gray89;
 @action-multiselect-menu-item__selected__background-color: @color-blue-clear-sky;
diff --git a/app/design/adminhtml/Magento/backend/web/css/source/components/_media-gallery.less b/app/design/adminhtml/Magento/backend/web/css/source/components/_media-gallery.less
index 35712c0c0bb74..db70b35de11fd 100644
--- a/app/design/adminhtml/Magento/backend/web/css/source/components/_media-gallery.less
+++ b/app/design/adminhtml/Magento/backend/web/css/source/components/_media-gallery.less
@@ -90,9 +90,7 @@
         height: @image-gallery-placeholder__height;
 
         .product-image-wrapper {
-            /**
-            * @codingStandardsIgnoreStart
-            */
+            /* @codingStandardsIgnoreStart */
             .lib-icon-font(
                 @icon-camera__content,
                 @_icon-font: @icons-admin__font-name,
@@ -100,7 +98,7 @@
                 @_icon-font-color: @image-gallery-placeholder-icon__color,
                 @_icon-font-text-hide: true
             );
-            //@codingStandardsIgnoreEnd
+            /* @codingStandardsIgnoreEnd */
 
             &:before {
                 left: 0;
diff --git a/app/design/adminhtml/Magento/backend/web/css/source/forms/_controls.less b/app/design/adminhtml/Magento/backend/web/css/source/forms/_controls.less
index c6f39e8e8840d..fb42991b4ff57 100644
--- a/app/design/adminhtml/Magento/backend/web/css/source/forms/_controls.less
+++ b/app/design/adminhtml/Magento/backend/web/css/source/forms/_controls.less
@@ -31,6 +31,7 @@
     width: auto;
 }
 
+/* @codingStandardsIgnoreStart */
 .__form-control-pattern__hover() {
     border-color: @field-control__hover__border-color;
 }
@@ -48,6 +49,7 @@
     cursor: not-allowed;
     opacity: @disabled__opacity;
 }
+/* @codingStandardsIgnoreEnd */
 
 //  Input text styles
 .admin__control-text {
@@ -134,12 +136,9 @@ option:empty {
     &:before {
         &:extend(.abs-form-control-pattern);
 
-        .admin__control-file:active + &,
-        .admin__control-file:focus + & {
-            /**
-             * @codingStandardsIgnoreStart
-             */
-            &:extend(.abs-form-control-pattern:focus);
+        .admin__control-file::active + &,
+        .admin__control-file::focus + & {
+            &:extend(.abs-form-control-pattern::focus);
         }
 
         .admin__control-file[disabled] + & {
@@ -168,14 +167,14 @@ option:empty {
 //  Support text. Can be used on label or plain text to align controls & actions
 //  ---------------------------------------------
 
-.admin__control-support-text { // ToDo UI: should be renamed to .admin__control-text
+.admin__control-support-text { /* ToDo UI: should be renamed to .admin__control-text */
     border: @field-control__border-width solid transparent;
     display: inline-block;
     font-size: @field-control__font-size;
     line-height: @field-control__line-height;
+    margin-left: @action__outer-indent;
     padding-bottom: @field-control__padding-bottom;
     padding-top: @field-control__padding-top;
-    margin-left: @action__outer-indent;
 
     + [class*='admin__control-'] {
         margin-left: @action__outer-indent;
@@ -288,11 +287,11 @@ option:empty {
         }
 
         &:focus ~ [class*='admin__addon-']:last-child:before {
-            &:extend(.abs-form-control-pattern:focus);
+            &:extend(.abs-form-control-pattern::focus);
         }
 
         &:hover ~ [class*='admin__addon-']:last-child:before {
-            &:extend(.abs-form-control-pattern:hover);
+            &:extend(.abs-form-control-pattern::hover);
         }
     }
 }
diff --git a/app/design/adminhtml/Magento/backend/web/css/source/forms/_fields.less b/app/design/adminhtml/Magento/backend/web/css/source/forms/_fields.less
index b86b0005e88fb..9c71d910b22cb 100644
--- a/app/design/adminhtml/Magento/backend/web/css/source/forms/_fields.less
+++ b/app/design/adminhtml/Magento/backend/web/css/source/forms/_fields.less
@@ -59,11 +59,9 @@
 }
 
 .abs-field-no-label {
-    /**
-     *@codingStandardsIgnoreStart
-     */
+    /* @codingStandardsIgnoreStart */
     #mix-grid .return_length(@field-label-grid__column, @field-grid__columns, '+');
-    //@codingStandardsIgnoreEnd
+    /* @codingStandardsIgnoreEnd */
     margin-left: @_length;
 }
 
@@ -121,7 +119,7 @@
 
         > .admin__field-control {
             #mix-grid .column(@field-control-grid__column, @field-grid__columns);
-            input[type="checkbox"] {
+            input[type='checkbox'] {
                 margin-top: @indent__s;
             }
         }
@@ -191,9 +189,11 @@
     .admin__control-textarea {
         width: 100%;
         &.disabled {
+            /* @codingStandardsIgnoreStart */
             background-color: #e9e9e9;
             border-color: #adadad;
             color: #303030;
+            /* @codingStandardsIgnoreEnd */
             cursor: not-allowed;
             opacity: .5;
         }
@@ -235,7 +235,9 @@
         white-space: nowrap;
 
         &:before {
+            /* @codingStandardsIgnoreStart */
             .appearing__off();
+            /* @codingStandardsIgnoreEnd */
             content: '.';
             margin-left: -7px;
             overflow: hidden;
@@ -328,7 +330,9 @@
     //  Till that time they'll be disabled by commenting pseudo-element content property.
     &[data-config-scope] {
         &:before {
+            /* @codingStandardsIgnoreStart */
             #mix-grid .return_length(@field-label-grid__column + @field-control-grid__column, @field-grid__columns);
+            /* @codingStandardsIgnoreEnd */
             color: @field-scope__color;
             content: attr(data-config-scope);
             display: inline-block;
@@ -349,8 +353,8 @@
     }
 
     &._error {
-        .admin__field-control [class*='admin__control-'] [class*='admin__addon-']:before,
-        .admin__field-control [class*='admin__addon-']:before,
+        .admin__field-control [class*='admin__control-'] [class*='admin__addon-']::before,
+        .admin__field-control [class*='admin__addon-']::before,
         .admin__field-control > [class*='admin__control-'] {
             border-color: @field-error-control__border-color;
         }
@@ -364,9 +368,11 @@
         outline: inherit;
 
         .admin__action-multiselect-wrap {
+            /* @codingStandardsIgnoreStart */
             .admin__action-multiselect {
                 .__form-control-pattern__disabled();
             }
+            /* @codingStandardsIgnoreEnd */
         }
     }
 
@@ -620,7 +626,7 @@
         &.admin__field-large {
             width: 1px;
 
-            + .admin__field:last-child {
+            + .admin__field::last-child {
                 width: auto;
             }
         }
@@ -666,8 +672,8 @@
         &.admin__field {
             > .admin__field-control {
                 &:extend(.abs-field-size-small all);
-                position: relative;
                 display: inline-block;
+                position: relative;
             }
         }
 
@@ -763,7 +769,7 @@
     margin: @indent__s 0 @indent__l;
     padding-left: @indent__s;
 
-    .admin__field:not(._hidden) + & {
+    .admin__field::not(._hidden) + & {
         margin-top: 3rem;
     }
 
@@ -809,7 +815,7 @@
 //  _____________________________________________
 
 .admin__legend {
-    //  ToDo UI: add form legend styles. Check if they doon't conflict with create order page form legend styles
+    /* ToDo UI: add form legend styles. Check if they doon't conflict with create order page form legend styles */
     float: left;
     position: static;
     width: 100%;
diff --git a/app/design/adminhtml/Magento/backend/web/css/source/forms/_temp.less b/app/design/adminhtml/Magento/backend/web/css/source/forms/_temp.less
index 71f57b765ff0e..fc1ce94614944 100644
--- a/app/design/adminhtml/Magento/backend/web/css/source/forms/_temp.less
+++ b/app/design/adminhtml/Magento/backend/web/css/source/forms/_temp.less
@@ -155,6 +155,8 @@
 
     .action-delete {
         .lib-button-reset();
+
+        /* @codingStandardsIgnoreStart */
         .lib-icon-font(
             @icon-remove-small__content,
             @icons-admin__font-name,
@@ -164,6 +166,7 @@
             @_icon-font-position: after,
             @_icon-font-color: @color-brown-darker
         );
+        /* @codingStandardsIgnoreEnd */
 
         span {
             max-height: 1px;
@@ -408,18 +411,15 @@ label.mage-error {
             width: 16px;
             z-index: 1;
 
-            /**
-             * @codingStandardsIgnoreStart
-             */
             &:before {
-                &:extend(.admin__control-checkbox + label:before);
+                &:extend(.admin__control-checkbox + label::before);
                 left: 0;
                 position: absolute;
                 top: 0;
             }
 
             &:after {
-                &:extend(.action-multicheck-wrap .action-multicheck-toggle:after);
+                &:extend(.action-multicheck-wrap .action-multicheck-toggle::after);
                 top: 40% !important;
             }
         }
@@ -427,7 +427,7 @@ label.mage-error {
         &:focus {
             + label {
                 &:after {
-                    &:extend(.action-multicheck-wrap .action-multicheck-toggle._active:after);
+                    &:extend(.action-multicheck-wrap .action-multicheck-toggle._active::after);
                 }
             }
         }
@@ -435,9 +435,8 @@ label.mage-error {
         &._checked {
             + label {
                 &:before {
-                    &:extend(.admin__control-checkbox:checked + label:before);
+                    &:extend(.admin__control-checkbox::checked + label::before);
                 }
-                //  @codingStandardsIgnoreEnd
             }
 
             &._indeterminate {
@@ -464,8 +463,8 @@ label.mage-error {
 
 .admin__data-grid-toolbar {
     *,
-    *:before,
-    *:after {
+    *::before,
+    *::after {
         box-sizing: border-box;
     }
 
diff --git a/app/design/adminhtml/Magento/backend/web/css/source/forms/fields/_control-table.less b/app/design/adminhtml/Magento/backend/web/css/source/forms/fields/_control-table.less
index 43e1bdaaef4e5..e4a84102f3f6b 100644
--- a/app/design/adminhtml/Magento/backend/web/css/source/forms/fields/_control-table.less
+++ b/app/design/adminhtml/Magento/backend/web/css/source/forms/fields/_control-table.less
@@ -6,9 +6,6 @@
 //
 //  Variables
 //  ---------------------------------------------
-/**
- * @codingStandardsIgnoreStart
- */
 @control-table__dragging__outline-color: @color-blue-pure;
 
 @control-table-row__dragging__background-color: @color-light-gray0;
@@ -239,6 +236,7 @@
     }
 }
 
+/* @codingStandardsIgnoreStart */
 .product_form_product_form_advanced_pricing_modal .admin__fieldset > .admin__field > .admin__field-label,
 .product_form_product_form_advanced_pricing_modal [class*='admin__control-grouped'] > .admin__field:first-child > .admin__field-label {
     margin-left: 0;
@@ -257,3 +255,4 @@
     overflow-x: visible;
     overflow-y: visible;
 }
+/* @codingStandardsIgnoreEnd */
diff --git a/app/design/frontend/Magento/blank/web/css/source/_extends.less b/app/design/frontend/Magento/blank/web/css/source/_extends.less
index aa934282ad7b6..d217601cb541d 100644
--- a/app/design/frontend/Magento/blank/web/css/source/_extends.less
+++ b/app/design/frontend/Magento/blank/web/css/source/_extends.less
@@ -11,9 +11,7 @@
 //  List default styles reset
 //  ---------------------------------------------
 
-/**
- * @codingStandardsIgnoreStart
- */
+/* @codingStandardsIgnoreStart */
 & when (@media-common = true) {
     .abs-reset-list {
         .lib-list-reset-styles();
@@ -1457,4 +1455,4 @@
         }
     }
 }
-//@codingStandardsIgnoreEnd
+/* @codingStandardsIgnoreEnd */
diff --git a/app/design/frontend/Magento/luma/Magento_Checkout/web/css/source/module/checkout/_payments.less b/app/design/frontend/Magento/luma/Magento_Checkout/web/css/source/module/checkout/_payments.less
index 8fbe67abe2960..c36a64f2ea884 100644
--- a/app/design/frontend/Magento/luma/Magento_Checkout/web/css/source/module/checkout/_payments.less
+++ b/app/design/frontend/Magento/luma/Magento_Checkout/web/css/source/module/checkout/_payments.less
@@ -67,13 +67,11 @@
                     }
                 }
             }
-            /**
-             * @codingStandardsIgnoreStart
-             */
+            /* @codingStandardsIgnoreStart */
             #po_number {
                 margin-bottom: 20px;
             }
-            //  @codingStandardsIgnoreEnd
+            /* @codingStandardsIgnoreEnd */
         }
 
         .payment-method-title {
@@ -138,7 +136,7 @@
                 .lib-css(padding, @checkout-billing-address-details__padding);
             }
 
-            input[type="checkbox"] {
+            input[type='checkbox'] {
                 vertical-align: top;
             }
         }