diff --git a/style.css b/style.css
index 262cdc7..d915bc7 100644
--- a/style.css
+++ b/style.css
@@ -417,3 +417,42 @@
   margin: 0 6px;
   white-space: nowrap;
 }
+
+/* ==============================
+   ゆるかわ吹き出し風 GroupBox
+============================== */
+
+#groupNameBox {
+  background: #ffffff;
+  border-radius: 22px;
+  padding: 18px 22px;
+  position: relative;
+  color: #444;
+  font-size: 15px;
+  font-weight: 500;
+  box-shadow: 0 6px 20px rgba(0,0,0,0.12);
+  line-height: 1.6;
+}
+
+/* 吹き出しの「しっぽ」 */
+#groupNameBox::before {
+  content: "";
+  position: absolute;
+  left: 24px;
+  bottom: -12px;
+  width: 20px;
+  height: 20px;
+  background: #ffffff;
+  border-radius: 4px;
+  transform: rotate(45deg);
+  box-shadow: 4px 4px 10px rgba(0,0,0,0.08);
+}
+
+/* うさぎアイコン */
+#groupNameBox::after {
+  content: "🐰";
+  position: absolute;
+  top: -18px;
+  left: 18px;
+  font-size: 26px;
+}