Hi cpisar ,
You can go and edit your css file.
Making child themes is more of a waste of time and making more work for the ones who want to code but why?
Pick the issue with firebug and go and edit this file to make css changes .
https://raheimdandre.com/wp-content/themes/twentythirteen/style.css
If you need to go into template files and you need to identify which file to edit you can use this website: WP theme hacks
Robert
