diff --git a/packages/web/src/components/dashboard/overview-stats.tsx b/packages/web/src/components/dashboard/overview-stats.tsx
index cce93b6..aa6e11d 100644
--- a/packages/web/src/components/dashboard/overview-stats.tsx
+++ b/packages/web/src/components/dashboard/overview-stats.tsx
@@ -85,15 +85,17 @@ export function OverviewStats({
       <button
         type="button"
         onClick={() => setExpanded(v => !v)}
+        aria-expanded={expanded}
+        aria-controls="overview-stats-explanation"
         className="mt-4 flex items-center gap-2 text-xs text-muted-foreground hover:text-foreground transition-colors"
       >
-        <span className={cn('inline-block transition-transform', expanded && 'rotate-90')}>▸</span>
+        <span className={cn('inline-block transition-transform', expanded && 'rotate-90')} aria-hidden="true">▸</span>
         <span className="font-medium text-foreground">What do these numbers mean?</span>
-        <span>— {expanded ? 'click to collapse' : 'click to expand'}</span>
+        <span aria-hidden="true">— {expanded ? 'click to collapse' : 'click to expand'}</span>
       </button>
 
       {expanded && (
-        <div className="mt-3 text-xs text-muted-foreground space-y-2 leading-relaxed">
+        <div id="overview-stats-explanation" className="mt-3 text-xs text-muted-foreground space-y-2 leading-relaxed">
           <p>
             <span className="font-medium text-foreground">Sessions</span> — 팀원들이 시작한 Claude Code 세션 수.
           </p>