diff --git a/src/client/app/desktop/views/components/post-form.vue b/src/client/app/desktop/views/components/post-form.vue
index 5dd40c9ba..b2a6fed8e 100644
--- a/src/client/app/desktop/views/components/post-form.vue
+++ b/src/client/app/desktop/views/components/post-form.vue
@@ -434,7 +434,7 @@ export default Vue.extend({
 </script>
 
 <style lang="stylus" scoped>
-root(isDark)
+.mk-post-form
 	display block
 	padding 16px
 	background var(--desktopPostFormBg)
@@ -677,7 +677,7 @@ root(isDark)
 		width 40px
 		height 40px
 		font-size 1em
-		color isDark ? var(--primary) : var(--primaryAlpha05)
+		color var(--desktopPostFormTransparentButtonFg)
 		background transparent
 		outline none
 		border solid 1px transparent
@@ -685,11 +685,11 @@ root(isDark)
 
 		&:hover
 			background transparent
-			border-color isDark ? var(--primaryAlpha05) : var(--primaryAlpha03)
+			border-color var(--primaryAlpha03)
 
 		&:active
 			color var(--primaryAlpha06)
-			background isDark ? transparent : linear-gradient(to bottom, var(--primaryLighten80) 0%, var(--primaryLighten90) 100%)
+			background linear-gradient(to bottom, var(--desktopPostFormTransparentButtonActiveGradientStart) 0%, var(--desktopPostFormTransparentButtonActiveGradientEnd) 100%)
 			border-color var(--primaryAlpha05)
 			box-shadow 0 2px 4px rgba(#000, 0.15) inset
 
@@ -714,10 +714,4 @@ root(isDark)
 		border dashed 2px var(--primaryAlpha05)
 		pointer-events none
 
-.mk-post-form[data-darkmode]
-	root(true)
-
-.mk-post-form:not([data-darkmode])
-	root(false)
-
 </style>
diff --git a/src/client/theme/dark.json b/src/client/theme/dark.json
index 97ec96827..ee5e1fb42 100644
--- a/src/client/theme/dark.json
+++ b/src/client/theme/dark.json
@@ -132,6 +132,9 @@
 	"desktopPostFormBg": "@face",
 	"desktopPostFormTextareaBg": "rgba(0, 0, 0, 0.25)",
 	"desktopPostFormTextareaFg": "#fff",
+	"desktopPostFormTransparentButtonFg": "$primary",
+	"desktopPostFormTransparentButtonActiveGradientStart": ":darken<8<$secondary",
+	"desktopPostFormTransparentButtonActiveGradientEnd": ":darken<3<$secondary",
 	"desktopRenoteFormFooter": ":lighten<5<$secondary",
 	"desktopTimelineHeaderShadow": "rgba(0, 0, 0, 0.15)",
 	"desktopTimelineSrc": "@faceTextButton",
diff --git a/src/client/theme/light.json b/src/client/theme/light.json
index 52822bc5f..4cfba2c1f 100644
--- a/src/client/theme/light.json
+++ b/src/client/theme/light.json
@@ -132,6 +132,9 @@
 	"desktopPostFormBg": ":lighten<33<$primary",
 	"desktopPostFormTextareaBg": "#fff",
 	"desktopPostFormTextareaFg": "#333",
+	"desktopPostFormTransparentButtonFg": ":alpha<0.5<$primary",
+	"desktopPostFormTransparentButtonActiveGradientStart": ":lighten<30<$primary",
+	"desktopPostFormTransparentButtonActiveGradientEnd": ":lighten<33<$primary",
 	"desktopRenoteFormFooter": ":lighten<33<$primary",
 	"desktopTimelineHeaderShadow": "rgba(0, 0, 0, 0.08)",
 	"desktopTimelineSrc": "#6f7477",