Removing incorrect less selector '.abs-cleafix', it has a typo + it is already used correctly in a different less file (_data-grid-header.less).

hostep · hostep · commit 3ad6bb9c3569 · 2019-04-06T11:16:24.000+02:00
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
@@ -470,8 +470,6 @@ label.mage-error {
     }
 
     .admin__data-grid-header-row {
-        &:extend(.abs-cleafix);
-
         .action-select-multiselect {
             -webkit-appearance: menulist-button;
             appearance: menulist-button;

Original file line number	Diff line number	Diff line change
`@@ -470,8 +470,6 @@ label.mage-error {`
`470`	`470`	`}`
`471`	`471`
`472`	`472`	`.admin__data-grid-header-row {`
`473`		`- &:extend(.abs-cleafix);`
`474`		`-`
`475`	`473`	`.action-select-multiselect {`
`476`	`474`	`-webkit-appearance: menulist-button;`
`477`	`475`	`appearance: menulist-button;`