Put mathematic divisions in less files in parentheses if they were not there already, this fixes generating correct css again after the upgrade to less.js v4 in AC-8098 & AC-9713.

Author: hostep

app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/_header.less

@@ -18,7 +18,7 @@
 //  ---------------------------------------------
 
 @page-header__indent-horizontal: @content__indent;
-@page-header__indent-vertical: @content__indent / 2;
+@page-header__indent-vertical: (@content__indent / 2);
 
 //
 

app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/_menu.less

@@ -181,7 +181,7 @@
     display: block;
     height: @menu-line-before__height;
     left: 0;
-    margin-left: (100% - @_menu-separator__width) / 2;
+    margin-left: ((100% - @_menu-separator__width) / 2);
     position: absolute;
     top: 0;
     width: @_menu-separator__width;

app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/header/_headings-group.less

@@ -27,7 +27,7 @@
 //
 
 .page-header-hgroup {
-    padding-right: @content__indent / 2;
+    padding-right: (@content__indent / 2);
 }
 
 //

app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/header/actions-group/_notifications.less

@@ -15,9 +15,9 @@
 @notifications__color: @color-gray20;
 
 @notifications-action__color: @text__color;
-@notifications-action__padding-bottom: (@page-header-action__height - @notifications-action-icon__size) / 2 - .05rem;
+@notifications-action__padding-bottom: ((@page-header-action__height - @notifications-action-icon__size) / 2 - .05rem);
 @notifications-action__padding-side: 2rem;
-@notifications-action__padding-top: (@page-header-action__height - @notifications-action-icon__size) / 2 + .05rem;
+@notifications-action__padding-top: ((@page-header-action__height - @notifications-action-icon__size) / 2 + .05rem);
 @notifications-action__hover__color: darken(@action-dropdown__color, 20%);
 @notifications-action-icon__size: 1.9rem;
 @notifications-action-menu__z-index: @header__z-index;
@@ -177,7 +177,7 @@
 .notifications-close {
     &:extend(.abs-action-reset all);
     line-height: 1;
-    padding: @notifications-action__padding-side / 2;
+    padding: (@notifications-action__padding-side / 2);
     position: absolute;
     right: 0;
     top: .6rem;

app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/header/actions-group/_search.less

@@ -17,8 +17,8 @@
 
 @search-global-input__font-size: @font-size__base;
 @search-global-input__height: @page-header-action__height;
-@search-global-input__padding-bottom: (@search-global-input__height - @search-global-icon__height) / 2 - .1rem;
-@search-global-input__padding-top: (@search-global-input__height - @search-global-icon__height) / 2 + .1rem;
+@search-global-input__padding-bottom: ((@search-global-input__height - @search-global-icon__height) / 2 - .1rem);
+@search-global-input__padding-top: ((@search-global-input__height - @search-global-icon__height) / 2 + .1rem);
 @search-global-input__padding-side: @font-size__base;
 @search-global-input__width: @search-global-icon__width + @search-global-input__padding-side * 2;
 

app/design/adminhtml/Magento/backend/Magento_Backend/web/css/source/module/pages/_dashboard.less

@@ -21,8 +21,8 @@
 @dashboard-secondary-table-col-name__width-px: 135px;
 @dashboard-secondary-table-col-value__width-px: 50px;
 
-@dashboard-secondary-table-col-name__width-pct: @dashboard-secondary-table-col-name__width-px * 100% / @dashboard-secondary-table__width-px; // 57.44680851%
-@dashboard-secondary-table-col-value__width-pct: @dashboard-secondary-table-col-value__width-px * 100% / @dashboard-secondary-table__width-px; // 21.27659574%
+@dashboard-secondary-table-col-name__width-pct: (@dashboard-secondary-table-col-name__width-px * 100% / @dashboard-secondary-table__width-px); // 57.44680851%
+@dashboard-secondary-table-col-value__width-pct: (@dashboard-secondary-table-col-value__width-px * 100% / @dashboard-secondary-table__width-px); // 21.27659574%
 
 //
 //  Tables
@@ -60,9 +60,9 @@
         @dashboard-table-col-name__width-px: 308px;
         @dashboard-table-col-value__width-px: 84px;
 
-        @dashboard-table-col-product__width-pct: @dashboard-table-col-product__width-px * 100% / @dashboard-table__width-px; // 70%
-        @dashboard-table-col-name__width-pct: @dashboard-table-col-name__width-px * 100% / @dashboard-table__width-px; // 55%
-        @dashboard-table-col-value__width-pct: @dashboard-table-col-value__width-px * 100% / @dashboard-table__width-px; // 15%
+        @dashboard-table-col-product__width-pct: (@dashboard-table-col-product__width-px * 100% / @dashboard-table__width-px); // 70%
+        @dashboard-table-col-name__width-pct: (@dashboard-table-col-name__width-px * 100% / @dashboard-table__width-px); // 55%
+        @dashboard-table-col-value__width-pct: (@dashboard-table-col-value__width-px * 100% / @dashboard-table__width-px); // 15%
 
         th,
         td {

app/design/adminhtml/Magento/backend/Magento_ConfigurableProduct/web/css/source/module/components/navigation-bar/_navigation-bar.less

@@ -90,9 +90,9 @@
         border-top: 1px solid @nav-bar-bullet-wrap__border-top-color;
         content: '';
         height: .8rem;
-        left: @nav-bar-step__width / 2;
+        left: (@nav-bar-step__width / 2);
         position: absolute;
-        right: @nav-bar-step__width / 2;
+        right: (@nav-bar-step__width / 2);
         top: @nav-bar-point__size;
     }
 
@@ -204,7 +204,7 @@
             position: absolute;
             right: auto;
             text-align: center;
-            top: @nav-bar-dot__size / 2 - (@nav-bar-point__size / 2) - @nav-bar-point__border-width + .05;
+            top: (@nav-bar-dot__size / 2 - (@nav-bar-point__size / 2) - @nav-bar-point__border-width + .05);
             width: @nav-bar-point__size;
         }
 

app/design/adminhtml/Magento/backend/Magento_ConfigurableProduct/web/css/source/module/steps/_attribute-values.less

@@ -18,7 +18,7 @@
 @steps-wizard-attribute-entity-action-save__content: @icon-arrow-right__content;
 @steps-wizard-attribute-entity-action-save__hover__content: @color-very-dark-gray-black2;
 
-@steps-wizard-attribute-option-width: 100%/3;
+@steps-wizard-attribute-option-width: (100%/3);
 
 //
 //  Common

app/design/adminhtml/Magento/backend/Magento_Marketplace/web/css/source/_module.less

@@ -20,7 +20,7 @@
     .partner {
         margin-bottom: @indent__xl;
         padding: 0 @indent__m;
-        width: 100% / 3;
+        width: (100% / 3);
     }
 }
 

app/design/adminhtml/Magento/backend/Magento_ProductVideo/web/css/source/_module.less

@@ -1,4 +1,4 @@
-// /**
+// /**
 //  * Copyright © Magento, Inc. All rights reserved.
 //  * See COPYING.txt for license details.
 //  */
@@ -28,7 +28,7 @@
 
     &:before {
         left: 0;
-        margin-top: -@video-gallery-icon__size / 2;
+        margin-top: (-@video-gallery-icon__size / 2);
         opacity: .5;
         position: absolute;
         right: 0;