diff --git a/themes/hugo-sustain/layouts/partials/head/css.html b/themes/hugo-sustain/layouts/partials/head/css.html
index 9fc6625..d442826 100644
--- a/themes/hugo-sustain/layouts/partials/head/css.html
+++ b/themes/hugo-sustain/layouts/partials/head/css.html
@@ -13,9 +13,10 @@
 
 <!-- Theme stylesheet, combination of all in assets/scss -->
 {{- $style := resources.Get "scss/main.scss" | resources.ExecuteAsTemplate "scss/main.scss" . | toCSS (dict "targetPath" "css/main.css" "enableSourceMap" false) }}
-<link rel="stylesheet" href="{{ ($style).RelPermalink }}?v={{ md5 time.Now.Unix }}">
+<link rel="stylesheet" href="{{ ($style).RelPermalink }}?v={{ md5 $style.Content }}">
 
 <!-- Custom CSS -->
 {{- range .Site.Params.custom_css }}
-<link rel="stylesheet" href="{{ relURL . }}?v={{ md5 time.Now.Unix }}" />
+{{- $md5 := md5 (readFile (printf "static/%s" .)) }}
+<link rel="stylesheet" href="{{ relURL . }}?v={{ $md5 }}" />
 {{- end }}