See here for icon :
https://sudonix.org/post/6686
Here my CSS for user level :
/*----------------------------------------------------------------------------*/
/*-------------- nodebb-plugin-user-level -----------------*/
/*----------------------------------------------------------------------------*/
/* style */
.user-level-topic {
vertical-align: middle;
border-radius: 0.25rem !important;
border: 2px solid var(--bs-user-level-border);
margin-left: 8px;
margin-right: 5px;
margin-top: -2px;
color: var(--bs-body-color-primary) !important;
background: var(--bs-user-level-bg) !important;
float: right;
font-size: 12px;
padding: 0px 10px !important;
font-weight: 600;
height: 23px !important;
}
/* Style on Profile page */
.level-index>div:first-child {
padding: 6px 15px 3px 15px;
border: 2px solid var(--bs-user-level-border);
border-radius: var(--bs-border-radius);
margin: 5px 28px 5px 0px;
color: var(--bs-link-color);
}
.level-index > div:first-child:before {
font-family: var(--bs-shoutbox-header-font-family) !important;
content: var(--bs-shoutbox-header-icon) !important;
margin-right: 8px;
}
/* icon, font */
.user-level-topic:before {
/* content: "\f521"; */
/* font-family: "Font Awesome 6 pro "; */
content: var(--bs-user-level-icon);
font-family: "Font Awesome 6 Pro";
margin-right: 5px;
font-weight: 600;
}
/* Popover Style */
.popover-body {
background: var(--bs-body-bg) !important;
color: var(--bs-body-color) !important;
border: 1px solid var(--bs-border-color);
border-radius: 0 0 0.375rem 0.375rem;
margin: 0px;
}
.popover-header {
border-top: 1px solid var(--bs-border-color);
border-left: 1px solid var(--bs-border-color);
border-right: 1px solid var(--bs-border-color);
background-color: var(--bs-alert-info-bg);
color: var(--bs-link-color);
border-top-left-radius: 0.375rem;
border-top-right-radius: 0.375rem;
margin: 0px;
}
.bs-popover-auto[data-popper-placement^=top]>.popover-arrow::after, .bs-popover-top>.popover-arrow::after,{
border-top-color: var(--bs-border-color);
}
.bs-popover-auto[data-popper-placement^=top]>.popover-arrow::after, .bs-popover-bottom>.popover-arrow::after,{
border-bottom-color: var(--bs-border-color);
}
.bs-popover-auto[data-popper-placement^=left]>.popover-arrow::after, .bs-popover-end>.popover-arrow::after {
border-left-color: var(--bs-border-color);
}
.bs-popover-auto[data-popper-placement^=right]>.popover-arrow::after, .bs-popover-end>.popover-arrow::after {
border-right-color: var(--bs-border-color);
}
and hack for user level on Account profile :