Images not displaying correctly and broken links

[TannerGilbert]

The images inside the Responsive Equations article aren't displayed correctly.

Furthermore 'See the Pen Responsive Equations: Collapse 2/2 by Peter Krautzberger (@pkra) on CodePen.' is mentioned twice.

Also lots of links don't exist anymore. Including:

• https://mathjax.github.io/MathJax-RespEq/Semantics-Lab/Semantics-Lab-MML.html
• https://mathjax.github.io/MathJax-RespEq/Semantics-Lab/Semantics-Lab-TeX.html