feat: add hashtag and mention functionality with corresponding plugins and styles

src/editor/styles/editor.css

@@ -351,3 +351,127 @@
 .editor-text-justify {
   text-align: justify;
 }
+
+/* Hashtag styles */
+.editor-hashtag {
+  background-color: rgba(88, 144, 255, 0.15);
+  border-bottom: 1px solid rgba(88, 144, 255, 0.3);
+  font-weight: 500;
+}
+
+/* Mention styles */
+.mention {
+  background-color: rgba(24, 119, 232, 0.2);
+  color: #1877e8;
+  border-radius: 4px;
+  padding: 1px 3px;
+  font-weight: 500;
+  cursor: pointer;
+}
+
+.mention:focus {
+  box-shadow: rgb(180 213 255) 0px 0px 0px 2px;
+  outline: none;
+}
+
+/* Typeahead popover styles */
+.typeahead-popover {
+  background: #fff;
+  box-shadow: 0px 5px 10px rgba(0, 0, 0, 0.3);
+  border-radius: 8px;
+  position: relative;
+  z-index: 5;
+}
+
+.typeahead-popover ul {
+  padding: 0;
+  list-style: none;
+  margin: 0;
+  border-radius: 8px;
+  max-height: 200px;
+  overflow-y: scroll;
+}
+
+.typeahead-popover ul::-webkit-scrollbar {
+  display: none;
+}
+
+.typeahead-popover ul {
+  -ms-overflow-style: none;
+  scrollbar-width: none;
+}
+
+.typeahead-popover ul li {
+  margin: 0;
+  min-width: 180px;
+  font-size: 14px;
+  outline: none;
+  cursor: pointer;
+  border-radius: 8px;
+}
+
+.typeahead-popover ul li.selected {
+  background: #eee;
+}
+
+.typeahead-popover li {
+  margin: 0 8px 0 8px;
+  padding: 8px;
+  color: #050505;
+  cursor: pointer;
+  line-height: 16px;
+  font-size: 15px;
+  display: flex;
+  align-content: center;
+  flex-direction: row;
+  flex-shrink: 0;
+  background-color: #fff;
+  border-radius: 8px;
+  border: 0;
+}
+
+.typeahead-popover li.active {
+  display: flex;
+  width: 20px;
+  height: 20px;
+  background-size: contain;
+}
+
+.typeahead-popover li:first-child {
+  border-radius: 8px 8px 0px 0px;
+}
+
+.typeahead-popover li:last-child {
+  border-radius: 0px 0px 8px 8px;
+}
+
+.typeahead-popover li:hover {
+  background-color: #eee;
+}
+
+.typeahead-popover li .text {
+  display: flex;
+  line-height: 20px;
+  flex-grow: 1;
+  min-width: 150px;
+}
+
+.typeahead-popover li .icon {
+  display: flex;
+  width: 20px;
+  height: 20px;
+  user-select: none;
+  margin-right: 8px;
+  line-height: 16px;
+  background-size: contain;
+  background-repeat: no-repeat;
+  background-position: center;
+}
+
+.mentions-menu {
+  width: 250px;
+}
+
+.typeahead-popover li .icon.user {
+  background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 24 24' fill='%23666'%3E%3Cpath d='M12 12c2.21 0 4-1.79 4-4s-1.79-4-4-4-4 1.79-4 4 1.79 4 4 4zm0 2c-2.67 0-8 1.34-8 4v2h16v-2c0-2.66-5.33-4-8-4z'/%3E%3C/svg%3E");
+}