/* 响应式 - 移动端 */
        @media (max-width: 768px) {
            .sidebar {
                position: fixed;
                top: 0;
                left: 0;
                height: 100%;
                width: 260px;
                transform: translateX(-100%);
                box-shadow: 4px 0 24px rgba(0, 0, 0, 0.3);
                z-index: 10;
                border-right: 1px solid var(--border-color);
            }
            .sidebar.overlay-mode {
                width: 260px;
            }
            .sidebar.push-mode.collapsed {
                width: 260px;
            }
            .sidebar:not(.collapsed) {
                transform: translateX(0);
            }
            .sidebar.collapsed {
                transform: translateX(-100%);
                pointer-events: none;
            }
            .sidebar.push-mode {
                position: fixed !important;
                transform: translateX(-100%);
            }
            .sidebar.push-mode:not(.collapsed) {
                transform: translateX(0);
            }
            .sidebar.push-mode.collapsed {
                transform: translateX(-100%);
                pointer-events: none;
                width: var(--sidebar-width);
            }

            .toggle-sidebar-btn {
                left: 16px !important;
                top: 10px !important;
                width: 36px;
                height: 36px;
                font-size: 18px;
            }

            .sidebar-header {
                padding-top: 10px;
            }
            .sidebar-header .new-btn {
                width: 36px;
                height: 36px;
                font-size: 18px;
            }
            .navbar-actions button {
                width: 36px;
                height: 36px;
                font-size: 16px;
            }

            .main-area {
                margin-left: 0 !important;
                width: 100%;
            }

            .chat-messages {
                padding: 14px 0 12px;
            }
            .chat-inner {
                max-width: 100%;
                padding: 0 12px;
            }
            .message, .message.user {
                flex-direction: column;
                flex-wrap: nowrap;
                align-items: flex-start;
                gap: 8px;
            }
            .message.user {
                align-items: flex-end;
            }
            .message .bubble {
                flex: none;
                max-width: 100%;
                font-size: 15px;
                padding: 14px 18px;
            }
            .message .msg-actions {
                flex: 0 0 auto;
                width: auto;
                padding-left: 12px;
            }
            .message.user .msg-actions {
                padding-left: 0;
                padding-right: 12px;
            }
            .message .bubble .content h1 { font-size: 1.7em; }
            .message .bubble .content h2 { font-size: 1.4em; }
            .message .bubble .content h3 { font-size: 1.2em; }

            .navbar {
                padding: 10px 14px;
            }
            .empty-state h2 {
                font-size: 30px;
            }
            .input-area {
                padding: 6px 12px 10px;
                max-width: 100%;
            }
            .input-area .input-wrapper {
                padding: 4px 4px 4px 14px;
                min-height: 54px;
            }
            .input-area textarea {
                min-height: 100px;
                padding-bottom: 64px;
                font-size: 15px;
            }
            .input-area .thinking-toggle {
                bottom: 14px;
                left: 14px;
                font-size: 14px;
                padding: 4px 14px;
                height: 28px;
                border-radius: 14px;
            }
            .input-area .send-btn {
                width: 40px;
                height: 40px;
                font-size: 16px;
            }
        }

        @media (max-width: 400px) {
            .navbar .title-display { max-width: 120px; font-size: 15px; }
            .empty-state h2 {
                font-size: 28px;
            }
            .message .bubble {
                padding: 12px 14px;
            }
            .message .bubble .content h1 { font-size: 1.5em; }
            .message .bubble .content h2 { font-size: 1.3em; }
            .message .bubble .content h3 { font-size: 1.1em; }
            .input-area textarea {
                min-height: 90px;
                padding-bottom: 56px;
            }
            .input-area .thinking-toggle {
                font-size: 13px;
                padding: 3px 12px;
                height: 26px;
                bottom: 10px;
                left: 10px;
            }
        }