diff --git a/src/css/edge.css b/src/css/edge.css
index f16e1b21..622a024c 100644
--- a/src/css/edge.css
+++ b/src/css/edge.css
@@ -7,7 +7,7 @@
   left: 0;
   opacity: 0;
   border-radius: var(--theme-radius);
-  box-shadow: inset 0 0 0 var(--layout-line-width) rgb(var(--theme-accent)), inset 0 0 0 calc(var(--layout-line-width) * 4) rgba(var(--theme-accent), 0.1), inset 0 0 0 calc(var(--layout-line-width) * 8) rgba(var(--theme-accent), 0.1);
+  box-shadow: var(--edge-shadow);
   z-index: var(--z-index-edge);
   pointer-events: none;
   transition: opacity var(--layout-timing-extra-fast);
diff --git a/src/css/variables.css b/src/css/variables.css
index 08c7c54d..54cbd145 100644
--- a/src/css/variables.css
+++ b/src/css/variables.css
@@ -166,6 +166,8 @@
   --button-link-text-focus-hover:                      var(--theme-style-text);
   --button-link-text-active:                           var(--theme-style-text);
   --button-link-text-disabled:                         var(--theme-gray-04);
+  /* edge */
+  --edge-shadow:                                       inset 0 0 0 var(--layout-line-width) rgb(var(--theme-accent)), inset 0 0 0 calc(var(--layout-line-width) * 4) rgba(var(--theme-accent), 0.1), inset 0 0 0 calc(var(--layout-line-width) * 8) rgba(var(--theme-accent), 0.1);
   /* font */
   --font-regular:                                      "Open Sans Regular", sans-serif;
   --font-bold:                                         "Open Sans Bold", sans-serif;