Fixed by placing a native button inside the heading, preserving its appearance and adding a visible keyboard focus outline

Enter and Space now trigger the existing comments action.

webui-src/app/boards/board_kanban.js

@@ -310,17 +310,15 @@ function BoardCard() {
             // Title (blue link matching Qt GUI)
             m(
               'h4.board-card__title',
-              {
+              m('button.board-card__title-button[type=button]', {
                 title,
-                tabindex: 0,
                 onclick: (e) => {
                   e.stopPropagation();
                   if (onOpenComments) {
                     onOpenComments(item, msgId, forumId);
                   }
                 },
-              },
-              title
+              }, title)
             ),
 
             // Metadata Line (Posted by <author> <date>)

webui-src/app/scss/pages/_board.scss

@@ -702,6 +702,22 @@ button.board-card__vote-btn,
   padding: 0 !important;
 }
 
+.board-card__title-button,
+.board-card__title-button:active {
+  all: unset;
+  box-sizing: border-box;
+  display: block;
+  width: 100%;
+  overflow: hidden;
+  text-overflow: ellipsis;
+  cursor: pointer;
+}
+
+.board-card__title-button:focus-visible {
+  outline: 2px solid currentColor;
+  outline-offset: -2px;
+}
+
 /* Title: Blue bold underlined italicized link (Matches Qt GUI) */
 .board-card--compact .board-card__title {
   font-size: 1.05rem !important;