/* ── CHAT APP — MOBILE ── */
  #mobileMenuBtn { display: none; }
  #sidebarBackdrop { display: none; }

  @media (max-width: 760px) {
    #mobileMenuBtn {
      display: flex;
      align-items: center;
      justify-content: center;
      position: fixed;
      top: 12px;
      left: 12px;
      width: 34px;
      height: 34px;
      border-radius: 7px;
      border: 1px solid #e0dcd6;
      background: #fff;
      z-index: 250;
      cursor: pointer;
    }
    #mobileMenuBtn svg { width: 16px; height: 16px; }

    aside {
      position: fixed;
      top: 0;
      left: 0;
      height: 100vh;
      z-index: 220;
      transform: translateX(-100%);
      transition: transform 0.2s ease;
      margin: 0;
      border-radius: 0;
      border: none;
      border-right: 1px solid #e5e1da;
    }
    aside.expanded {
      transform: translateX(0);
      box-shadow: 4px 0 24px rgba(0,0,0,0.25);
    }

    #sidebarBackdrop.show {
      display: block;
      position: fixed;
      inset: 0;
      background: rgba(0,0,0,0.4);
      z-index: 210;
    }

    .topbar { padding: 12px 16px 12px 56px; }
    .empty { padding: 64px 20px 20px; }
    .empty h2 { font-size: 22px; }

    .input-center { max-width: 100%; }

    .messages { padding: 56px 16px 16px; }
    .msg-user { padding: 10px 14px; max-width: 86%; }

    .bottom-bar { padding: 0 12px 16px; }
    .input-toolbar { flex-wrap: wrap; row-gap: 6px; }
  }