Fix dark mode styling issues

Author: Tenchi2xh

example.md

@@ -7,7 +7,7 @@ footer: Example slides
 
 # Appearance
 # Uncomment for dark mode
-# class: invert
+class: invert
 transition: wipe
 
 # Don't change
@@ -31,7 +31,7 @@ math: mathjax
 Scan to follow along or keep the link for later:
 
 <!-- Update this link with the name of your slides instead of 'example' -->
-![w:256px](https://api.qrserver.com/v1/create-qr-code/?data=code-star.github.io/codestar-marp/example/&size=512x512&bgcolor=f1e7da)
+![w:256px](https://api.qrserver.com/v1/create-qr-code/?data=code-star.github.io/codestar-marp/example/&size=512x512&bgcolor=f1e7da&margin=16)
 
 *Link to the slides*
 

theme/codestar.css

@@ -143,7 +143,7 @@ section:has(> h1), section:has(> h2), section:has(.title) {
     }
   }
 }
-:root.invert .title div:nth-child(2)::after {
+:root.invert .title div:first-child::after {
   background-image: url("#{$url-base}/theme/logo/logo_red_dark_transparent_tagline.png");
 }