Last Reviewed: 27-Apr-15 (3.3.20) 3.1.* 3.2.* 3.3.*
Where to copy/paste this code?
The simplest way is to use the Custom CSS section of the customizer option screen. If you have many customizations to make in CSS and PHP, then we strongly recommend you create a child theme. Everything you need to know about creating a child theme with Customizr here.
/* START OF Add a border underneath the Slider */
/* 2px=thickness, solid=style (dotted-dashed-solid-double-groove-ridge-inset-outset), red=color */
border-bottom: 2px solid red;
/* END OF Add a border underneath the Slider */