A user style for better styling for the duplicate link icon of the ClutterFree extension.

clutterfree-duplicate-link-icon.user.css

/* ==UserStyle==
@name        ClutterFree duplicate link icon facelift
@description Better styling for the duplicate link icon of the ClutterFree extension.
@author      Hazem AbuMostafa (http://hazemam.com)
@homepageURL https://gist.github.com/HazemAM/cb5808c96991a4762528f1752e28c8d3
@updateURL   https://gist.github.com/HazemAM/cb5808c96991a4762528f1752e28c8d3/raw/clutterfree-duplicate-link-icon.user.css
@namespace   github.com/hazemam
@version     1.1.1
@license     Apache-2.0

@var  number  size  "Icon size"  [15, 0, null, 1, 'px']
==/UserStyle== */

:root {
    --reverse-size: calc(var(--size) * -1);
}

a.clutterFree_existingDuplicate.cf_div_theme_light:not(.clutterFree_noIcon),
a.clutterFree_existingDuplicate.cf_div_theme_dark:not(.clutterFree_noIcon) {
    position: relative;
}

a.clutterFree_existingDuplicate.cf_div_theme_light:not(.clutterFree_noIcon)::after,
a.clutterFree_existingDuplicate.cf_div_theme_dark:not(.clutterFree_noIcon)::after {
    content: '';
    position: absolute;
    height: var(--size);
    width: var(--size);
    
    right: var(--reverse-size);
    top: calc(var(--reverse-size) / 2);
    
    z-index: 999;

    opacity: 1;
    box-shadow: 0 2px 6px rgba(0, 0, 0, 0.5);
    border-radius: 50%;
    
    background-size: calc(var(--size) - 2px);
    background-repeat: no-repeat;
    background-position: center center;
    
    transition: opacity 0.25s ease;
}

a.clutterFree_existingDuplicate.cf_div_theme_light:not(.clutterFree_noIcon)::after {
    background-color: white;
    background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24'><path d='M6 17h3l2-4V7H5v6h3zm8 0h3l2-4V7h-6v6h3z' fill='black'/><path d='M0 0h24v24H0z' fill='none'/></svg>");
}
a.clutterFree_existingDuplicate.cf_div_theme_dark:not(.clutterFree_noIcon)::after {
    background-color: black;
    background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' width='24' height='24' viewBox='0 0 24 24'><path d='M6 17h3l2-4V7H5v6h3zm8 0h3l2-4V7h-6v6h3z' fill='white'/><path d='M0 0h24v24H0z' fill='none'/></svg>");
}

a.clutterFree_existingDuplicate.cf_div_theme_light:not(.clutterFree_noIcon):hover::after {
    background-color: hsla(200, 75%, 95%, 1);
}
a.clutterFree_existingDuplicate.cf_div_theme_dark:not(.clutterFree_noIcon):hover::after {
    background-color: hsla(200, 75%, 5%, 1);
}