diff --git a/source/css/_common/header.styl b/source/css/_common/header.styl
index 291ba9c379c6da0ea1e66ba4899d86d24d0e117f..2fccb4864e57170172f409cd5bc9720633da30be 100644
--- a/source/css/_common/header.styl
+++ b/source/css/_common/header.styl
@@ -1,6 +1,7 @@
+$header-height = convert(hexo-config('header.height') || '80vh')
 if (hexo-config('header.height'))
-  $header-height = unit(
-    convert(hexo-config('header.height') || '80%'), 'vh')
+  if (match('%', hexo-config('header.height')))
+    $header-height = unit(convert(hexo-config('header.height')), 'vh')
 
 #header
   display: flex
@@ -27,8 +28,10 @@ $header-nav-color
       &::after
         color: $header-nav-link-hover-color
 
-$header-nav-height = convert(
-  hexo-config('header.nav_height') || '50px')
+$header-nav-height = convert(hexo-config('header.nav_height') || '50px')
+if (hexo-config('header.nav_height'))
+  if (match('%', hexo-config('header.nav_height')))
+    $header-nav-height = unit(convert(hexo-config('header.nav_height')), 'vh')
 
 .header-nav
   position: fixed