Unable to add color border to bottom of Customizr Slider

Hi,
I’ve tried adding the code below as instructed in the Forum to add a bottom border to the customizr slider, but a border doesn’t appear whether I’m using the code given or adding another HEX color. I’ve also tried modifying it so that it reflects the name given to the slider on the home page, but that still doesn’t work. Can you let me know what I’m doing wrong?

Here’s the code that was provided, but it isn’t working:
/* 2px=thickness, solid=style (dotted – dashed – solid – double – groove – ridge – inset – outset), #000=color */
#customizr-slider {
border-bottom: 2px solid red;
}
Here’s the modification I made, but it isn’t working:
/* 2px=thickness, solid=style (dotted – dashed – solid – double – groove – ridge – inset – outset), #000=color */
#customizr-slider {
border-bottom: 2px solid #27CBCD;
}
and finally, here’s another approach, but it isn’t working:
/* 2px=thickness, solid=style (dotted – dashed – solid – double – groove – ridge – inset – outset), #000=color */
#welcome-slider {
border-bottom: 2px solid #27CBCD;
}

Thanks in advance for your help.