Customize Styles
There are various options available to modify theme styles.
Theme Options - Go to Dashboard → Appearance → Theme Options → Styles for various styles related sections.
Quick CSS - Go to Dashboard → Appearance → Theme Options → Styles → Quick CSS to add small css changes.
Custom CSS in Child Theme - 'child-custom.css' file is provided in child theme to add big css changes.
Custom CSS in Parent Theme - if you are not using child theme then 'css/custom.css' file is provided in parent theme to add big css changes.