left: 0;
        width: 100%;
        height: 100%;
        background-image: url("[[${theme.config.basic.background_dark_mode}]]");
        background-position: top center;
        background-size: cover;
        background-repeat: no-repeat;
        z-index: -1; /* 保证内容层在背景之上 */
      }

      [/]
      [# th:if="${theme.config.basic.enable_background_dark != true} or ${theme.config.basic.background_dark_mode == ''} or ${theme.config.basic.background_dark_mode == null}"]
      html[dat