diff --git a/frontend/src/pages/ChallengeDetail.jsx b/frontend/src/pages/ChallengeDetail.jsx
index b824bc5..b435ccb 100644
--- a/frontend/src/pages/ChallengeDetail.jsx
+++ b/frontend/src/pages/ChallengeDetail.jsx
@@ -320,7 +320,7 @@ export default function ChallengeDetail() {
                         className="btn btn-primary btn-sm"
                         onClick={() => handleInvite(friend.id, friend.username)}
                         disabled={inviting === friend.id}
-                        style={{ flexShrink: 0 }}
+                        style={{ flexShrink: 0, width: 'auto' }}
                       >
                         {inviting === friend.id ? 'Inviting...' : 'Invite'}
                       </button>
@@ -376,7 +376,7 @@ export default function ChallengeDetail() {
                       className="btn btn-primary btn-sm"
                       onClick={() => handleInvite(user.id, user.username)}
                       disabled={inviting === user.id}
-                      style={{ flexShrink: 0 }}
+                      style={{ flexShrink: 0, width: 'auto' }}
                     >
                       {inviting === user.id ? 'Inviting...' : 'Invite'}
                     </button>