Replace Obsidian hashtag in tags to a custom emoji. [Not tested on Obsidian 1.0+]

replace-hashtag-with-emoji.css

a.tag,
.kanban-plugin .kanban-plugin__item-tags .kanban-plugin__item-tag {
    position: relative;
    display: inline-block;
    margin: .125em;
}
a.tag::before,
.cm-formatting-hashtag::before {
    font-size: .85em;
    content: "🌺";
    display: inline-block;
    position: relative;
    z-index: .5;
    right: -.7em;
    padding: 0 2px 0 0;
    background-color: var(--background-primary);
}