diff --git a/assets/css/_schemes/Pisces/_sidebar.scss b/assets/css/_schemes/Pisces/_sidebar.scss
index 4d6e9b1..d3ec63c 100644
--- a/assets/css/_schemes/Pisces/_sidebar.scss
+++ b/assets/css/_schemes/Pisces/_sidebar.scss
@@ -83,7 +83,7 @@
   // Only when back2top.sidebar is true, apply the following styles
   .back-to-top {
     background: var(--body-bg-color);
-    margin: 8px - $sidebar-offset -10px -18px;
+    margin: 8px -#{$sidebar-offset} -10px -18px;
 
     &.back-to-top-on {
       margin-top: 16px;