Improve cookie banner design.

assets/scss/main.scss

@@ -10,5 +10,13 @@ $dark: #535455;
 $link-decoration: none;
 $link-color: $secondary;
 
+:root {
+  --cookie-banner-bg: #cad2e0;
+  --cookie-banner-color: #17293c;
+  --cookie-accept-bg: #16a34a;
+  --cookie-decline-bg: #dc2626;
+  --cookie-banner-shadow: 0 0 36px #686a6f;
+}
+
 @import "hugo_bootstrap_theme";
 @import "hugo_cookie_consent";