Try this code in extra.less and see if it works for you.XF2.3 Compatibility?
Code:
/* Sticky Thread Container */
.structItemContainer-group--sticky {
border-left: 4px solid var(--xf-borderColorAccent, @xf-borderColor);
padding: 12px;
margin-bottom: 10px;
background: linear-gradient(135deg, var(--xf-stickyBackground, @xf-contentBg) 0%, var(--xf-stickyBackgroundAlt, @xf-paletteColor1) 100%);
box-shadow: 0 2px 8px var(--xf-shadowColor, rgba(0, 0, 0, 0.15));
border-radius: 8px;
transition: background-color 0.3s, box-shadow 0.3s, border-color 0.3s;
}
/* Sticky Icon */
.structItem-status--sticky::before {
content: "\f08d"; /* Sticky Pin Icon */
font-family: "Font Awesome 5 Free";
font-weight: 900;
color: var(--xf-stickyIconColor, @xf-linkColor);
margin-right: 8px;
font-size: 16px;
}
/* Sticky Text Color */
.structItem-status--sticky {
color: var(--xf-stickyTextColor, @xf-textColorMuted);
}
/* Golden Separator Line */
.structItemContainer-group--sticky + .structItemContainer-group--nonsticky {
border-top: 4px solid var(--xf-goldenSeparator, #FFD700);
margin-top: 15px;
padding-top: 15px;
}
/* Dark Theme Adjustments */
html[theme="dark"] .structItemContainer-group--sticky {
background: linear-gradient(135deg, var(--xf-stickyBackgroundDark, #2b2b2b) 0%, var(--xf-stickyBackgroundAltDark, #1c1c1c) 100%);
box-shadow: 0 2px 8px var(--xf-shadowColorDark, rgba(255, 255, 255, 0.1));
}
html[theme="dark"] .structItem-status--sticky::before {
color: var(--xf-stickyIconColorDark, #f5f5f5);
}
html[theme="dark"] .structItem-status--sticky {
color: var(--xf-stickyTextColorDark, #f5f5f5);
}
/* Dark Theme Golden Separator */
html[theme="dark"] .structItemContainer-group--sticky + .structItemContainer-group--nonsticky {
border-top: 4px solid var(--xf-goldenSeparatorDark, #FFCC00);
}