feat: implement light mode theme for osv.dev web frontend

Author: tymzd

gcp/website/blog/hugo.toml

@@ -2,6 +2,6 @@ baseURL = 'http://osv.dev/blog/'
 languageCode = 'en-us'
 title = 'OSV Blog'
 [markup]
-[markup.highlight]
-style = 'native'
-tabWidth = 2
+  [markup.highlight]
+    noClasses = false
+    tabWidth = 2

gcp/website/blog/layouts/index.html

@@ -5,7 +5,7 @@
   <div class="author">Posted by {{ .Params.author }} on {{ .PublishDate.Format "Jan 2, 2006" }}</div>
   <div class="summary">
     {{ .Summary }}
-    <p><a href="{{ .Permalink | relURL }}">Read more...</a></p>
+    <p><a class="read-more" href="{{ .Permalink | relURL }}">Read more...</a></p>
   </div>
 </div>
 {{ end }}