diff --git a/src/css/app/core/mixin/_entry-content.scss b/src/css/app/core/mixin/_entry-content.scss
index acee52ee..df0b620c 100644
--- a/src/css/app/core/mixin/_entry-content.scss
+++ b/src/css/app/core/mixin/_entry-content.scss
@@ -34,14 +34,14 @@
 
 @mixin entry-content-theme() {
 	// @see app/setup/customizer-styles.php
-	> h2 {
+	> :where(h2) {
 		border-left: var(--entry-content-h2-border-left);
 		background-color: var(--entry-content-h2-background-color);
 		padding: var(--entry-content-h2-padding);
 	}
 
 	// @see app/setup/customizer-styles.php
-	> h3 {
+	> :where(h3) {
 		border-bottom: var(--entry-content-h3-border-bottom);
 		padding: var(--entry-content-h3-padding);
 	}
diff --git a/src/css/app/object/component/_widget/_widget-text/_app-theme.scss b/src/css/app/object/component/_widget/_widget-text/_app-theme.scss
index c0a49d2f..c619ce1f 100644
--- a/src/css/app/object/component/_widget/_widget-text/_app-theme.scss
+++ b/src/css/app/object/component/_widget/_widget-text/_app-theme.scss
@@ -1,5 +1,5 @@
 @use '../../../../core/mixin/entry-content' as *;
 
-.textwidget {
+:where(.textwidget) {
 	@include entry-content-theme();
 }
diff --git a/src/css/app/object/project/_entry-content/_app-theme.scss b/src/css/app/object/project/_entry-content/_app-theme.scss
index 2ac99ff4..adbf87a1 100644
--- a/src/css/app/object/project/_entry-content/_app-theme.scss
+++ b/src/css/app/object/project/_entry-content/_app-theme.scss
@@ -1,5 +1,5 @@
 @use '../../../core/mixin/entry-content' as *;
 
-.p-entry-content {
+:where(.p-entry-content) {
 	@include entry-content-theme();
 }
diff --git a/src/css/block-editor/app-theme.scss b/src/css/block-editor/app-theme.scss
index df9ad027..9be2b7de 100644
--- a/src/css/block-editor/app-theme.scss
+++ b/src/css/block-editor/app-theme.scss
@@ -1,8 +1,10 @@
 @use 'sass:meta';
 @use '../app/core/mixin/entry-content' as *;
 
-.is-root-container,
-.wp-block-freeform {
+:where(
+	.is-root-container,
+	.wp-block-freeform
+) {
 	@include entry-content-theme();
 }
 
diff --git a/src/css/block-library/_layout/_app-theme.scss b/src/css/block-library/_layout/_app-theme.scss
index 5b314e33..5412ae21 100644
--- a/src/css/block-library/_layout/_app-theme.scss
+++ b/src/css/block-library/_layout/_app-theme.scss
@@ -1,7 +1,9 @@
 @use '../../app/core/mixin/entry-content' as *;
 
-.is-layout-constrained,
-.is-layout-flow {
+:where(
+	.is-layout-constrained,
+	.is-layout-flow
+) {
 	@include entry-content-theme();
 }
 
diff --git a/src/css/block-library/_wp-block-heading/_app.scss b/src/css/block-library/_wp-block-heading/_app.scss
index 605b8672..8c891a02 100644
--- a/src/css/block-library/_wp-block-heading/_app.scss
+++ b/src/css/block-library/_wp-block-heading/_app.scss
@@ -1,4 +1,5 @@
-.wp-block-heading.is-style-plain {
+.wp-block-heading:where(.is-style-plain),
+.wp-block-heading:where([class*="is-style-snow-monkey-"]) {
 	--entry-content-h2-background-color: transparent;
 	--entry-content-h2-border-left: none;
 	--wp--preset--color--sm-text: inherit;
diff --git a/src/css/block-library/_wp-block-latest-posts/_app-theme.scss b/src/css/block-library/_wp-block-latest-posts/_app-theme.scss
index 3d8b0678..dd7dbbc5 100644
--- a/src/css/block-library/_wp-block-latest-posts/_app-theme.scss
+++ b/src/css/block-library/_wp-block-latest-posts/_app-theme.scss
@@ -1,12 +1,10 @@
 @use '../../app/core/mixin/entry-content' as *;
 
-.wp-block-latest-posts {
-	&__post-full-content {
-		@include entry-content-theme();
+:where(.wp-block-latest-posts__post-full-content) {
+	@include entry-content-theme();
+}
 
-		// For editor
-		> div:not([class]) {
-			@include entry-content-theme();
-		}
-	}
+// For editor
+:where(.wp-block-latest-posts__post-full-content > div:not([class])) {
+	@include entry-content-theme();
 }
diff --git a/src/css/block-library/_wp-block-media-text/_app-theme.scss b/src/css/block-library/_wp-block-media-text/_app-theme.scss
index 2c4e08c6..bb8ff274 100644
--- a/src/css/block-library/_wp-block-media-text/_app-theme.scss
+++ b/src/css/block-library/_wp-block-media-text/_app-theme.scss
@@ -1,7 +1,5 @@
 @use '../../app/core/mixin/entry-content' as *;
 
-.wp-block-media-text {
-	&__content {
-		@include entry-content-theme();
-	}
+:where(.wp-block-media-text__content) {
+	@include entry-content-theme();
 }
diff --git a/src/css/dependency/snow-monkey-forms/app-theme.scss b/src/css/dependency/snow-monkey-forms/app-theme.scss
index 74413596..fa910fd3 100644
--- a/src/css/dependency/snow-monkey-forms/app-theme.scss
+++ b/src/css/dependency/snow-monkey-forms/app-theme.scss
@@ -1,8 +1,10 @@
 @use '../../app/core/mixin/entry-content' as *;
 
-.smf-complete-content,
-.smf-system-error-content,
-.smf-item__controls {
+:where(
+	.smf-complete-content,
+	.smf-system-error-content,
+	.smf-item__controls
+) {
 	@include entry-content-theme();
 }