diff --git a/core/package.json b/core/package.json
index 672caa5d708ad26eceda1b0471bac825b7f27775..bc00280799107ab00656f6d07ca664642e600086 100644
--- a/core/package.json
+++ b/core/package.json
@@ -91,7 +91,7 @@
     "sortablejs": "1.15.x",
     "stylelint": "^14.0.1",
     "stylelint-checkstyle-formatter": "^0.1.2",
-    "stylelint-config-standard": "^23.0.0",
+    "stylelint-config-standard": "^28.0.0",
     "stylelint-order": "^5.0.0",
     "tabbable": "~6.0.0",
     "terser": "^5.14.2",
diff --git a/core/themes/claro/css/components/details.css b/core/themes/claro/css/components/details.css
index f12e867dc12135f7f295ff6d0c4cc3ad08e13388..c56e8b28dc1f7d7729ac7c98237cf767e49faca7 100644
--- a/core/themes/claro/css/components/details.css
+++ b/core/themes/claro/css/components/details.css
@@ -337,11 +337,11 @@ td .claro-details {
  * Merges standard collapse-processed selectors.
  */
 
-[open] > .claro-details__summary--accordion:not(:focus):not(:active)::after,
-[open] > .claro-details__summary--accordion-item:not(:focus):not(:active)::after,
+[open] > .claro-details__summary--accordion:not(:focus, :active)::after,
+[open] > .claro-details__summary--accordion-item:not(:focus, :active)::after,
 .collapse-processed[open] > .claro-details__summary--accordion .details-title:not(:focus)::after,
 .collapse-processed[open] > .claro-details__summary--accordion-item .details-title:not(:focus)::after,
-[open] > .claro-details__summary--vertical-tabs-item:not(:focus):not(:active)::after,
+[open] > .claro-details__summary--vertical-tabs-item:not(:focus, :active)::after,
 .collapse-processed[open] > .claro-details__summary--vertical-tabs-item .details-title:not(:focus)::after {
   opacity: 1;
   border: var(--details-summary-focus-border-size) solid var(--color-absolutezero);
diff --git a/core/themes/claro/css/components/details.pcss.css b/core/themes/claro/css/components/details.pcss.css
index e6e7de2792cda77326a3346e032f5bbc59c760da..531928c994a96f8c422ffcdda8c5335ee1aa17b3 100644
--- a/core/themes/claro/css/components/details.pcss.css
+++ b/core/themes/claro/css/components/details.pcss.css
@@ -316,11 +316,11 @@
  * Active has to be here for Firefox.
  * Merges standard collapse-processed selectors.
  */
-[open] > .claro-details__summary--accordion:not(:focus):not(:active)::after,
-[open] > .claro-details__summary--accordion-item:not(:focus):not(:active)::after,
+[open] > .claro-details__summary--accordion:not(:focus, :active)::after,
+[open] > .claro-details__summary--accordion-item:not(:focus, :active)::after,
 .collapse-processed[open] > .claro-details__summary--accordion .details-title:not(:focus)::after,
 .collapse-processed[open] > .claro-details__summary--accordion-item .details-title:not(:focus)::after,
-[open] > .claro-details__summary--vertical-tabs-item:not(:focus):not(:active)::after,
+[open] > .claro-details__summary--vertical-tabs-item:not(:focus, :active)::after,
 .collapse-processed[open] > .claro-details__summary--vertical-tabs-item .details-title:not(:focus)::after {
   opacity: 1;
   border: var(--details-summary-focus-border-size) solid var(--color-absolutezero);
diff --git a/core/themes/claro/css/components/jquery.ui/theme.css b/core/themes/claro/css/components/jquery.ui/theme.css
index 9fc9a8ceb69992533e82cfdf5630d6529c64f613..5038079996d92e13d6e834b67e1825c964b12390 100644
--- a/core/themes/claro/css/components/jquery.ui/theme.css
+++ b/core/themes/claro/css/components/jquery.ui/theme.css
@@ -61,13 +61,11 @@
 .ui-state-disabled,
 .ui-widget-content .ui-state-disabled {
   opacity: 0.35;
-  filter: alpha(opacity=35);
 }
 
 .ui-priority-secondary,
 .ui-widget-content .ui-priority-secondary {
   opacity: 0.7;
-  filter: alpha(opacity=70);
 }
 
 /**
diff --git a/core/themes/claro/css/components/jquery.ui/theme.pcss.css b/core/themes/claro/css/components/jquery.ui/theme.pcss.css
index 6a742c801702994701e48dbd07eb2092645c6b1f..5f4199a3d71e9f4c1b8de05728b2a2e9e02973e9 100644
--- a/core/themes/claro/css/components/jquery.ui/theme.pcss.css
+++ b/core/themes/claro/css/components/jquery.ui/theme.pcss.css
@@ -47,12 +47,10 @@
 .ui-state-disabled,
 .ui-widget-content .ui-state-disabled {
   opacity: 0.35;
-  filter: alpha(opacity=35);
 }
 .ui-priority-secondary,
 .ui-widget-content .ui-priority-secondary {
   opacity: 0.7;
-  filter: alpha(opacity=70);
 }
 
 /**
diff --git a/core/themes/olivero/css/components/comments.css b/core/themes/olivero/css/components/comments.css
index 083711799d6520482bbf7480b803a0af9d313cbc..6f4d858d796915cd1c45e9b0af55eea62c73f1fb 100644
--- a/core/themes/olivero/css/components/comments.css
+++ b/core/themes/olivero/css/components/comments.css
@@ -311,23 +311,23 @@
   margin-right: var(--comment-indentation);
 }
 
-[dir="ltr"] .indented > .comment:not(:last-of-type):not(.has-children):before {
+[dir="ltr"] .indented > .comment:not(:last-of-type, .has-children):before {
     left: calc(-1 * var(--comment-indentation) - var(--sp));
 }
 
-[dir="rtl"] .indented > .comment:not(:last-of-type):not(.has-children):before {
+[dir="rtl"] .indented > .comment:not(:last-of-type, .has-children):before {
     right: calc(-1 * var(--comment-indentation) - var(--sp));
 }
 
-[dir="ltr"] .indented > .comment:not(:last-of-type):not(.has-children):before {
+[dir="ltr"] .indented > .comment:not(:last-of-type, .has-children):before {
     border-left: solid 1px var(--color--gray-95);
 }
 
-[dir="rtl"] .indented > .comment:not(:last-of-type):not(.has-children):before {
+[dir="rtl"] .indented > .comment:not(:last-of-type, .has-children):before {
     border-right: solid 1px var(--color--gray-95);
 }
 
-.indented > .comment:not(:last-of-type):not(.has-children):before {
+.indented > .comment:not(:last-of-type, .has-children):before {
     position: absolute;
     top: var(--sp2); /* Comment's padding-top */
     width: 0;
@@ -337,11 +337,11 @@
 
 @media (min-width: 43.75rem) {
 
-[dir="ltr"] .indented > .comment:not(:last-of-type):not(.has-children):before {
+[dir="ltr"] .indented > .comment:not(:last-of-type, .has-children):before {
       left: calc(-1 * var(--comment-indentation--md) + var(--sp));
   }
 
-[dir="rtl"] .indented > .comment:not(:last-of-type):not(.has-children):before {
+[dir="rtl"] .indented > .comment:not(:last-of-type, .has-children):before {
       right: calc(-1 * var(--comment-indentation--md) + var(--sp));
   }
     }
diff --git a/core/themes/olivero/css/components/comments.pcss.css b/core/themes/olivero/css/components/comments.pcss.css
index 01ba00f9094a6990fa366d42fccb75795e0a8e3e..c45e14180ca75c0d6173de70229c808e60f7040c 100644
--- a/core/themes/olivero/css/components/comments.pcss.css
+++ b/core/themes/olivero/css/components/comments.pcss.css
@@ -183,7 +183,7 @@
 .indented {
   margin-inline-start: var(--comment-indentation);
 
-  & > .comment:not(:last-of-type):not(.has-children):before {
+  & > .comment:not(:last-of-type, .has-children):before {
     position: absolute;
     inset-block-start: var(--sp2);
     inset-inline-start: calc(-1 * var(--comment-indentation) - var(--sp)); /* Comment's padding-top */
diff --git a/core/yarn.lock b/core/yarn.lock
index 3f9f2cde2cd89c94059b4916c746070fc4990aa5..2cdd8707668c67abdd42b9adf7644adbe3f93027 100644
--- a/core/yarn.lock
+++ b/core/yarn.lock
@@ -4985,17 +4985,17 @@ stylelint-checkstyle-formatter@^0.1.2:
   dependencies:
     lodash "^4.17.10"
 
-stylelint-config-recommended@^6.0.0:
-  version "6.0.0"
-  resolved "https://registry.yarnpkg.com/stylelint-config-recommended/-/stylelint-config-recommended-6.0.0.tgz#fd2523a322836005ad9bf473d3e5534719c09f9d"
-  integrity sha512-ZorSSdyMcxWpROYUvLEMm0vSZud2uB7tX1hzBZwvVY9SV/uly4AvvJPPhCcymZL3fcQhEQG5AELmrxWqtmzacw==
+stylelint-config-recommended@^9.0.0:
+  version "9.0.0"
+  resolved "https://registry.yarnpkg.com/stylelint-config-recommended/-/stylelint-config-recommended-9.0.0.tgz#1c9e07536a8cd875405f8ecef7314916d94e7e40"
+  integrity sha512-9YQSrJq4NvvRuTbzDsWX3rrFOzOlYBmZP+o513BJN/yfEmGSr0AxdvrWs0P/ilSpVV/wisamAHu5XSk8Rcf4CQ==
 
-stylelint-config-standard@^23.0.0:
-  version "23.0.0"
-  resolved "https://registry.yarnpkg.com/stylelint-config-standard/-/stylelint-config-standard-23.0.0.tgz#4ad58c74804c544cb4d30667c21a30ab14d1c17d"
-  integrity sha512-8PDlk+nWuc1T66nVaODTdVodN0pjuE5TBlopi39Lt9EM36YJsRhqttMyUhnS78oc/59Q6n8iw2GJB4QcoFqtRg==
+stylelint-config-standard@^28.0.0:
+  version "28.0.0"
+  resolved "https://registry.yarnpkg.com/stylelint-config-standard/-/stylelint-config-standard-28.0.0.tgz#7e1926c232631a8445eafee7b186d276d42d7b15"
+  integrity sha512-q/StuowDdDmFCravzGHAwgS9pjX0bdOQUEBBDIkIWsQuYGgYz/xsO8CM6eepmIQ1fc5bKdDVimlJZ6MoOUcJ5Q==
   dependencies:
-    stylelint-config-recommended "^6.0.0"
+    stylelint-config-recommended "^9.0.0"
 
 stylelint-order@^5.0.0:
   version "5.0.0"