打开IDEA的设置 editor->code style->HTML->other->Do not indent children of
删掉html>head>body>这几项就可以了。
!DOCTYPE html>
html lang="en" xmlns:th="http://www.thymeleaf.org">
head>
meta charset="UTF-8">
title>websocket聊天室/title>
link th:href="@{/webjars/bootstrap/4.4.1/css/bootstrap.min.css}" rel="external nofollow" rel="stylesheet">
/head>
body>
div class="container">
!-- Content here -->
/div>
/body>
/html>
