.message-bubble {
        animation: fadeIn 0.3s ease-in;
      }

      @keyframes fadeIn {
        from {
          opacity: 0;
          transform: translateY(10px);
        }
        to {
          opacity: 1;
          transform: translateY(0);
        }
      }

      .typing-indicator {
        display: inline-flex;
        gap: 4px;
        align-items: center;
      }

      .typing-indicator span {
        width: 6px;
        height: 6px;
        border-radius: 50%;
        background-color: #475d5b;
        animation: typing 1.4s infinite ease-in-out;
      }

      .typing-indicator span:nth-child(1) {
        animation-delay: -0.32s;
      }
      .typing-indicator span:nth-child(2) {
        animation-delay: -0.16s;
      }

      @keyframes typing {
        0%,
        80%,
        100% {
          transform: scale(0);
          opacity: 0.5;
        }
        40% {
          transform: scale(1);
          opacity: 1;
        }
      }

      /* 文本选择菜单 */
      .selection-menu {
        position: fixed;
        background: #00473e;
        color: #f2f7f5;
        border: 1px solid #00332c;
        border-radius: 8px;
        padding: 6px;
        box-shadow: 0 6px 20px rgba(0, 0, 0, 0.2);
        z-index: 1000;
        display: flex;
        flex-direction: column;
        gap: 4px;
      }

      /* 模态框层级高于选择菜单 */
      .modal-overlay {
        z-index: 1050 !important;
      }

      .selection-menu button {
        font-size: 12px;
        padding: 6px 12px;
        border-radius: 6px;
        border: 1px solid #00332c;
        background: #00473e;
        color: #f2f7f5;
        cursor: pointer;
        transition: all 0.2s;
        width: 100%;
        text-align: left;
      }

      .selection-menu button:hover {
        background: #faae2b;
        border-color: #00473e;
        color: #00473e;
      }

      /* 高亮样式 */
      .vocab-highlight {
        background-color: #faae2b;
        border-radius: 3px;
        padding: 0 2px;
        margin: 0 1px;
        cursor: help;
      }

      .grammar-highlight {
        background-color: #f2f7f5;
        border-radius: 4px;
        padding: 2px 4px;
        margin: 0 2px;
        box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1), 0 1px 2px rgba(0, 0, 0, 0.06);
        cursor: pointer;
      }

      /* Popover 样式 */
      .popover {
        position: fixed;
        background: #f2f7f5;
        color: #00473e;
        font-size: 12px;
        padding: 12px;
        border: 1px solid #e5e7eb;
        border-radius: 8px;
        box-shadow: 0 6px 20px rgba(0, 0, 0, 0.15);
        z-index: 1001;
        max-width: 300px;
        white-space: pre-line;
      }

      .popover-header {
        position: relative;
        display: flex;
        align-items: center;
        justify-content: space-between;
        margin-bottom: 8px;
      }

      .popover h4 {
        font-weight: 600;
        margin: 0;
        font-size: 14px;
        flex: 1;
      }

      .popover-close {
        position: absolute;
        top: -4px;
        right: -4px;
        width: 20px;
        height: 20px;
        display: flex;
        align-items: center;
        justify-content: center;
        background: #f3f4f6;
        border: 1px solid #e5e7eb;
        color: #00473e;
        border-radius: 50%;
        cursor: pointer;
        font-size: 14px;
        line-height: 1;
        padding: 0;
      }

      .popover-close:hover {
        background: #faae2b;
      }

      .popover-edit {
        position: absolute;
        top: -4px;
        right: 20px;
        width: 20px;
        height: 20px;
        display: flex;
        align-items: center;
        justify-content: center;
        background: #f3f4f6;
        border: 1px solid #e5e7eb;
        color: #00473e;
        border-radius: 50%;
        cursor: pointer;
        font-size: 12px;
        line-height: 1;
        padding: 0;
      }

      .popover-edit:hover {
        background: #e5e7eb;
      }

      .popover p {
        margin: 4px 0;
        color: #475d5b;
      }

      /* 建议问题样式 */
      .suggestion-chip {
        display: inline-block;
        padding: 6px 12px;
        margin: 4px;
        background: #f2f7f5;
        border: 1px solid #00332c;
        border-radius: 16px;
        font-size: 13px;
        cursor: pointer;
        transition: all 0.2s;
      }

      .suggestion-chip:hover {
        background: #e5e7eb;
        border-color: #00332c;
        transform: translateY(-1px);
      }

      /* 自定义消息提示样式 */
      .toast-container {
        position: fixed;
        top: 20px;
        left: 50%;
        transform: translateX(-50%);
        z-index: 2000;
        display: flex;
        flex-direction: column;
        gap: 10px;
        pointer-events: none;
      }

      .toast-message {
        background: #00473e;
        color: #f2f7f5;
        padding: 12px 20px;
        border-radius: 8px;
        box-shadow: 0 4px 12px rgba(0, 0, 0, 0.15);
        min-width: 300px;
        max-width: 500px;
        animation: slideDown 0.3s ease-out;
        pointer-events: auto;
        position: relative;
        display: flex;
        align-items: center;
        justify-content: space-between;
        gap: 12px;
      }

      .toast-message.success {
        background: #00473e;
      }

      .toast-message.error {
        background: #fa5246;
      }

      .toast-message.warning {
        background: #faae2b;
      }

      .toast-message.info {
        background: #475d5b;
      }

      @keyframes slideDown {
        from {
          opacity: 0;
          transform: translateY(-20px);
        }
        to {
          opacity: 1;
          transform: translateY(0);
        }
      }

      .toast-close {
        background: rgba(242, 247, 245, 0.2);
        border: none;
        color: #f2f7f5;
        width: 20px;
        height: 20px;
        border-radius: 50%;
        cursor: pointer;
        display: flex;
        align-items: center;
        justify-content: center;
        flex-shrink: 0;
        padding: 0;
        font-size: 14px;
        line-height: 1;
        transition: background 0.2s;
      }

      .toast-close:hover {
        background: rgba(242, 247, 245, 0.3);
      }

      .toast-content {
        flex: 1;
        word-wrap: break-word;
      }