diff --git a/packages/frontend/src/components/MkChannelPreview.vue b/packages/frontend/src/components/MkChannelPreview.vue
index c30cb66c07..3c0874a1eb 100644
--- a/packages/frontend/src/components/MkChannelPreview.vue
+++ b/packages/frontend/src/components/MkChannelPreview.vue
@@ -117,7 +117,7 @@ const bannerStyle = computed(() => {
 			left: 0;
 			width: 100%;
 			height: 64px;
-			background: linear-gradient(0deg, var(--panel), var(--X15));
+			background: linear-gradient(0deg, var(--panel), color(from var(--panel) srgb r g b / 0));
 		}
 
 		> .name {
diff --git a/packages/frontend/src/components/MkContainer.vue b/packages/frontend/src/components/MkContainer.vue
index a399acd47f..8ad653a0bf 100644
--- a/packages/frontend/src/components/MkContainer.vue
+++ b/packages/frontend/src/components/MkContainer.vue
@@ -216,7 +216,7 @@ onUnmounted(() => {
 			left: 0;
 			width: 100%;
 			height: 64px;
-			background: linear-gradient(0deg, var(--panel), var(--X15));
+			background: linear-gradient(0deg, var(--panel), color(from var(--panel) srgb r g b / 0));
 
 			> .fadeLabel {
 				display: inline-block;
diff --git a/packages/frontend/src/components/MkNote.vue b/packages/frontend/src/components/MkNote.vue
index 32d1cc5640..4caafe54bf 100644
--- a/packages/frontend/src/components/MkNote.vue
+++ b/packages/frontend/src/components/MkNote.vue
@@ -859,7 +859,7 @@ function emitUpdReaction(emoji: string, delta: number) {
 	z-index: 2;
 	width: 100%;
 	height: 64px;
-	background: linear-gradient(0deg, var(--panel), var(--X15));
+	background: linear-gradient(0deg, var(--panel), color(from var(--panel) srgb r g b / 0));
 
 	&:hover > .collapsedLabel {
 		background: var(--panelHighlight);
diff --git a/packages/frontend/src/components/MkOmit.vue b/packages/frontend/src/components/MkOmit.vue
index 100a025653..ee1f15c189 100644
--- a/packages/frontend/src/components/MkOmit.vue
+++ b/packages/frontend/src/components/MkOmit.vue
@@ -62,7 +62,7 @@ onUnmounted(() => {
 			left: 0;
 			width: 100%;
 			height: 64px;
-			background: linear-gradient(0deg, var(--panel), var(--X15));
+			background: linear-gradient(0deg, var(--panel), color(from var(--panel) srgb r g b / 0));
 
 			> .fadeLabel {
 				display: inline-block;
diff --git a/packages/frontend/src/components/MkSubNoteContent.vue b/packages/frontend/src/components/MkSubNoteContent.vue
index 9a07826f1a..25412cc2e5 100644
--- a/packages/frontend/src/components/MkSubNoteContent.vue
+++ b/packages/frontend/src/components/MkSubNoteContent.vue
@@ -62,7 +62,7 @@ const collapsed = ref(isLong);
 			left: 0;
 			width: 100%;
 			height: 64px;
-			background: linear-gradient(0deg, var(--panel), var(--X15));
+			background: linear-gradient(0deg, var(--panel), color(from var(--panel) srgb r g b / 0));
 
 			> .fadeLabel {
 				display: inline-block;
diff --git a/packages/frontend/src/pages/channel.vue b/packages/frontend/src/pages/channel.vue
index 3c3ff08aee..7e7b724023 100644
--- a/packages/frontend/src/pages/channel.vue
+++ b/packages/frontend/src/pages/channel.vue
@@ -310,7 +310,7 @@ definePageMetadata(() => ({
 	left: 0;
 	width: 100%;
 	height: 64px;
-	background: linear-gradient(0deg, var(--panel), var(--X15));
+	background: linear-gradient(0deg, var(--panel), color(from var(--panel) srgb r g b / 0));
 }
 
 .bannerStatus {
diff --git a/packages/frontend/src/pages/welcome.timeline.note.vue b/packages/frontend/src/pages/welcome.timeline.note.vue
index f385938343..6a9ecd9a62 100644
--- a/packages/frontend/src/pages/welcome.timeline.note.vue
+++ b/packages/frontend/src/pages/welcome.timeline.note.vue
@@ -84,7 +84,7 @@ onUpdated(() => {
 		left: 0;
 		width: 100%;
 		height: 64px;
-		background: linear-gradient(0deg, var(--panel), var(--X15));
+		background: linear-gradient(0deg, var(--panel), color(from var(--panel) srgb r g b / 0));
 	}
 }
 
diff --git a/packages/frontend/src/themes/_dark.json5 b/packages/frontend/src/themes/_dark.json5
index a310fb716f..0dcb81e44d 100644
--- a/packages/frontend/src/themes/_dark.json5
+++ b/packages/frontend/src/themes/_dark.json5
@@ -89,7 +89,6 @@
 		X11: 'rgba(0, 0, 0, 0.3)',
 		X12: 'rgba(255, 255, 255, 0.1)',
 		X13: 'rgba(255, 255, 255, 0.15)',
-		X15: ':alpha<0<@panel',
 		X16: ':alpha<0.7<@panel',
 		X17: ':alpha<0.8<@bg',
 	},
diff --git a/packages/frontend/src/themes/_light.json5 b/packages/frontend/src/themes/_light.json5
index 827a935a0b..74063a447a 100644
--- a/packages/frontend/src/themes/_light.json5
+++ b/packages/frontend/src/themes/_light.json5
@@ -89,7 +89,6 @@
 		X11: 'rgba(0, 0, 0, 0.1)',
 		X12: 'rgba(0, 0, 0, 0.1)',
 		X13: 'rgba(0, 0, 0, 0.15)',
-		X15: ':alpha<0<@panel',
 		X16: ':alpha<0.7<@panel',
 		X17: ':alpha<0.8<@bg',
 	},