Making Slider Fade in Customizr theme

Hi Guys,

New here, I copied and pasted the code given into Customizing ? Advanced options Additional CSS .

This code.
/* START OF Change Slider to Fader */
/* Make Carousel fade – adapt 2s to required delay */
.carousel-inner > .item {
-webkit-transition: opacity 2s ease-in-out ;
transition: opacity 2s ease-in-out ;
}
.carousel-inner > .next.left,
.carousel-inner > .prev.right {
opacity: 1;
z-index: 1;
left: 0;
}
.carousel-inner > .active.left {
opacity: 0;
z-index: 2;
left: 0;
}
.carousel-inner > .active.right {
opacity: 0;
z-index: 2;
left: 0;
}

/* remove previous/next arrows from home page only */
.home .carousel-control {
display: none ;
}
/* END OF Change Slider to Fader */

didn’t work?. Then I made a child theme and put the code into the CSS there still doesn’t work and gave me this error?. ERROR: Template is missing. Standalone themes need to have a index.php template file. Child themes need to have a Template header in the style.css stylesheet.

Sorry new please can someone help me on this. Much appreciated