fixing more links

Author: mattmakai

content/pages/04-web-development/17-css.markdown

@@ -119,6 +119,14 @@ web application's design.
   provides advice on how to write simpler, easier-to-maintain CSS code
   to reduce your need to rely on CSS preprocessors and build pipelines.
 
+* [How to Detect Unused CSS or JavaScript](https://javascript.plainenglish.io/detect-unused-css-or-javascript-in-your-code-8d200ef07e50)
+  explains how to use [Chrome DevTools](https://developer.chrome.com/docs/devtools/)
+  to analyze a page's CSS and identify parts that are not used. Note that
+  even though a specific page does not use that CSS (or JS), there might
+  be another page that uses the same CSS files and *does* use that "unused"
+  code, so test your pages before and after making the changes to ensure
+  you did not inadvertently break something else!
+
 * [CSS refresher notes](https://github.com/vasanthk/css-refresher-notes) is
   incredibly helpful if you've learned CSS in bits and pieces along the way
   and you now want to fill in the gaps in your knowledge.

content/pages/05-deployment/09-paas.markdown

@@ -69,11 +69,6 @@ of controlling and modifying the project for your own applications,
 but prevents you from offloading the responsibility of keeping servers
 running to someone else.
 
-* [Kel](http://www.kelproject.com/) uses Kubernetes as a foundation
-  for a custom self-hosted PaaS. Note that it was created by Eldarion,
-  which had one of the first Python-specific PaaS offerings on the
-  market around the time that Heroku was launched.
-
 * [Dokku](http://dokku.viewdocs.io/dokku/) builds on Docker and has
   hooks for plugins to extend the small core of the project and customize 
   deployments for your applications.
@@ -82,7 +77,6 @@ running to someone else.
   designed to run on top of AWS services.
 
 
-
 ## Platform-as-a-service resources
 * [The differences between IaaS, PaaS and SaaS](https://www.engineyard.com/blog/the-differences-between-iaas-paas-and-saas-and-when-to-use-each)
   explains the abstract layer differences among "X-as-a-service" offering