diff --git a/core/.stylelintrc.json b/core/.stylelintrc.json
index 832748d391..82e18698ac 100644
--- a/core/.stylelintrc.json
+++ b/core/.stylelintrc.json
@@ -18,7 +18,6 @@
     "function-linear-gradient-no-nonstandard-direction": null,
     "function-name-case": null,
     "function-whitespace-after": null,
-    "length-zero-no-unit": null,
     "no-empty-source": null,
     "no-unknown-animations": true,
     "number-leading-zero": null,
diff --git a/core/modules/outside_in/css/outside_in.table.css b/core/modules/outside_in/css/outside_in.table.css
index dc6bb89502..e2d1b1e557 100644
--- a/core/modules/outside_in/css/outside_in.table.css
+++ b/core/modules/outside_in/css/outside_in.table.css
@@ -31,7 +31,7 @@
   height: 35px;
   vertical-align: middle;
   text-align: left; /* LTR */
-  border: 0px;
+  border: 0;
   border-style: solid;
   border-color: #777;
   border-bottom-width: 1px;
diff --git a/core/modules/outside_in/css/outside_in.theme.css b/core/modules/outside_in/css/outside_in.theme.css
index 0db7a3ce40..8d20f3297e 100644
--- a/core/modules/outside_in/css/outside_in.theme.css
+++ b/core/modules/outside_in/css/outside_in.theme.css
@@ -154,15 +154,15 @@
   margin: 0;
   /* Push the text away from the icon. */
   padding-left: 30px; /* LTR */
-  padding-right: 0px; /* LTR */
+  padding-right: 0; /* LTR */
   /* Ensure that long titles do not overlap the close button. */
   max-width: 210px;
   text-align: left; /* LTR */
 }
 [dir="rtl"] .ui-dialog-outside-in .ui-dialog-title {
   text-align: right;
-  padding-left: 0px;
-  padding-right: 0px;
+  padding-left: 0;
+  padding-right: 0;
 }
 .ui-dialog-outside-in .ui-dialog-title:before {
   background: transparent url(../../../misc/icons/ffffff/pencil.svg) no-repeat scroll center center;
diff --git a/core/modules/quickedit/css/quickedit.theme.css b/core/modules/quickedit/css/quickedit.theme.css
index 120573a57b..802ef7130a 100644
--- a/core/modules/quickedit/css/quickedit.theme.css
+++ b/core/modules/quickedit/css/quickedit.theme.css
@@ -26,7 +26,7 @@
 }
 .quickedit-editing.quickedit-validation-error,
 .quickedit-form.quickedit-validation-error {
-  box-shadow: 0 0 0px 1px #ee8b74, 0 0 0 2px #fa2209;
+  box-shadow: 0 0 0 1px #ee8b74, 0 0 0 2px #fa2209;
 }
 .quickedit-editing.quickedit-editor-is-popup {
   box-shadow: none;
@@ -121,7 +121,7 @@
 .quickedit-toolbar-container > .quickedit-toolbar-pointer {
   background-color: #e4e4e4;
   bottom: 2px;
-  box-shadow: 0 0 0 1px #818181, 0px 0px 0 4px rgba(150, 150, 150, 0.5);
+  box-shadow: 0 0 0 1px #818181, 0 0 0 4px rgba(150, 150, 150, 0.5);
   display: block;
   height: 16px;
   left: 18px; /* LTR */
@@ -142,7 +142,7 @@
 }
 .quickedit-toolbar-container > .quickedit-toolbar-lining {
   bottom: 7px;
-  box-shadow: 0 0 0 1px #818181, 0px 3px 0px 1px rgba(150, 150, 150, 0.5);
+  box-shadow: 0 0 0 1px #818181, 0 3px 0 1px rgba(150, 150, 150, 0.5);
   display: block;
   left: 0;
   position: absolute;
diff --git a/core/modules/simpletest/css/simpletest.module.css b/core/modules/simpletest/css/simpletest.module.css
index c0079b6ec3..9235b4958c 100644
--- a/core/modules/simpletest/css/simpletest.module.css
+++ b/core/modules/simpletest/css/simpletest.module.css
@@ -84,7 +84,7 @@ a.simpletest-collapse {
 a.simpletest-collapse:focus,
 a.simpletest-collapse:hover {
   font-size: 80%;
-  top: 0px;
+  top: 0;
   height: auto;
   width: auto;
   overflow: visible;
diff --git a/core/modules/system/css/components/ajax-progress.module.css b/core/modules/system/css/components/ajax-progress.module.css
index 136c2e1207..41c8ed8a7c 100644
--- a/core/modules/system/css/components/ajax-progress.module.css
+++ b/core/modules/system/css/components/ajax-progress.module.css
@@ -11,7 +11,7 @@
   float: right;
 }
 .ajax-progress-throbber .throbber {
-  background: transparent url(../../../../misc/throbber-active.gif) no-repeat 0px center;
+  background: transparent url(../../../../misc/throbber-active.gif) no-repeat 0 center;
   display: inline;
   padding: 1px 5px 2px;
 }
diff --git a/core/modules/system/css/system.admin.css b/core/modules/system/css/system.admin.css
index be739ac11d..b82a08ec8b 100644
--- a/core/modules/system/css/system.admin.css
+++ b/core/modules/system/css/system.admin.css
@@ -118,7 +118,7 @@ small .admin-link:after {
 }
 .system-modules td details a {
   color: #5C5C5B;
-  border: 0px;
+  border: 0;
 }
 .system-modules td details {
   border: 0;
diff --git a/core/themes/classy/css/components/collapse-processed.css b/core/themes/classy/css/components/collapse-processed.css
index 3ed2e35713..ba394342f6 100644
--- a/core/themes/classy/css/components/collapse-processed.css
+++ b/core/themes/classy/css/components/collapse-processed.css
@@ -8,7 +8,7 @@
   padding-right: 0.5em;
 }
 .collapse-processed > summary:before {
-  background: url(../../../../misc/menu-expanded.png) 0px 100% no-repeat; /* LTR */
+  background: url(../../../../misc/menu-expanded.png) 0 100% no-repeat; /* LTR */
   content: "";
   float: left; /* LTR */
   height: 1em;
diff --git a/core/themes/stable/css/quickedit/quickedit.theme.css b/core/themes/stable/css/quickedit/quickedit.theme.css
index 120573a57b..802ef7130a 100644
--- a/core/themes/stable/css/quickedit/quickedit.theme.css
+++ b/core/themes/stable/css/quickedit/quickedit.theme.css
@@ -26,7 +26,7 @@
 }
 .quickedit-editing.quickedit-validation-error,
 .quickedit-form.quickedit-validation-error {
-  box-shadow: 0 0 0px 1px #ee8b74, 0 0 0 2px #fa2209;
+  box-shadow: 0 0 0 1px #ee8b74, 0 0 0 2px #fa2209;
 }
 .quickedit-editing.quickedit-editor-is-popup {
   box-shadow: none;
@@ -121,7 +121,7 @@
 .quickedit-toolbar-container > .quickedit-toolbar-pointer {
   background-color: #e4e4e4;
   bottom: 2px;
-  box-shadow: 0 0 0 1px #818181, 0px 0px 0 4px rgba(150, 150, 150, 0.5);
+  box-shadow: 0 0 0 1px #818181, 0 0 0 4px rgba(150, 150, 150, 0.5);
   display: block;
   height: 16px;
   left: 18px; /* LTR */
@@ -142,7 +142,7 @@
 }
 .quickedit-toolbar-container > .quickedit-toolbar-lining {
   bottom: 7px;
-  box-shadow: 0 0 0 1px #818181, 0px 3px 0px 1px rgba(150, 150, 150, 0.5);
+  box-shadow: 0 0 0 1px #818181, 0 3px 0 1px rgba(150, 150, 150, 0.5);
   display: block;
   left: 0;
   position: absolute;
diff --git a/core/themes/stable/css/simpletest/simpletest.module.css b/core/themes/stable/css/simpletest/simpletest.module.css
index c0079b6ec3..9235b4958c 100644
--- a/core/themes/stable/css/simpletest/simpletest.module.css
+++ b/core/themes/stable/css/simpletest/simpletest.module.css
@@ -84,7 +84,7 @@ a.simpletest-collapse {
 a.simpletest-collapse:focus,
 a.simpletest-collapse:hover {
   font-size: 80%;
-  top: 0px;
+  top: 0;
   height: auto;
   width: auto;
   overflow: visible;
diff --git a/core/themes/stable/css/system/components/ajax-progress.module.css b/core/themes/stable/css/system/components/ajax-progress.module.css
index f1caf3ad0d..8e335c4e02 100644
--- a/core/themes/stable/css/system/components/ajax-progress.module.css
+++ b/core/themes/stable/css/system/components/ajax-progress.module.css
@@ -11,7 +11,7 @@
   float: right;
 }
 .ajax-progress-throbber .throbber {
-  background: transparent url(../../../images/core/throbber-active.gif) no-repeat 0px center;
+  background: transparent url(../../../images/core/throbber-active.gif) no-repeat 0 center;
   display: inline;
   padding: 1px 5px 2px;
 }
diff --git a/core/themes/stable/css/system/system.admin.css b/core/themes/stable/css/system/system.admin.css
index 6f5f62b804..37a33b4ce8 100644
--- a/core/themes/stable/css/system/system.admin.css
+++ b/core/themes/stable/css/system/system.admin.css
@@ -118,7 +118,7 @@ small .admin-link:after {
 }
 .system-modules td details a {
   color: #5C5C5B;
-  border: 0px;
+  border: 0;
 }
 .system-modules td details {
   border: 0;