title: Java. Thymeleaf. After CRUD operation all .CSS styles on page disappearing
body: <p>A have simple CRUD web application. And I want to bind UI and backend with thymeleaf. After I create some data and get server response - all styles are disappearing. I'm new to thymeleaf, CSS and HTML. Can someone help me to figure out where is the problem? 
  <strong>Before and after</strong>: 
  <a href="https://i.stack.imgur.com/6wbtD.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/6wbtD.jpg" alt="enter image description here"></a>
  <a href="https://i.stack.imgur.com/7Zwun.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7Zwun.jpg" alt="enter image description here"></a></p>
  
  <p>Save operation method:</p>
  
  <pre><code>  @PostMapping("/user/save")
      public ModelAndView save(@ModelAttribute("userDTO") @Valid UserDTO userDTO,
                               BindingResult bindingResult, WebRequest request, Errors errors) {
          User registered = new User();
          if (!bindingResult.hasErrors()) {
              registered = createUserAccount(userDTO, bindingResult);
          }
          if (registered == null) {
              bindingResult.rejectValue("email", "message.regError");
          }
          if (bindingResult.hasErrors()) {
              bindingResult.getAllErrors().forEach(error -&gt; log.error(error.toString()));
              return new ModelAndView("authorization/registration", "error", bindingResult.getAllErrors());
          } else {
              return new ModelAndView("users", "user", userDTO);
          }
      }
  </code></pre>
  
  <p>registration.html</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html lang="en" xmlns:th="http://www.thymeleaf.org"&gt;
  
  &lt;head&gt;
      &lt;meta charset="UTF-8"&gt;
      &lt;title&gt;User Registration&lt;/title&gt;
      &lt;div th:replace="fragments/css_fragments :: css_background_layer"&gt;&lt;/div&gt;
  &lt;/head&gt;
  
  &lt;body&gt;
  &lt;div style="text-align:center"&gt;
      &lt;div th:replace="fragments/menu_fragments :: header_menu"&gt;&lt;/div&gt;
  &lt;/div&gt;
  &lt;div style="margin: 0 auto; width: 20%; padding-top: 18%;"&gt;
      &lt;div class="registration-form"&gt;
          &lt;!--/*@thymesVar id="userDTO" type="com.socnetw.socnetw.model.UserDTO"*/--&gt;
          &lt;form id="form" method="post" action="/user/save" th:object="${userDTO}"&gt;
              &lt;label&gt;
                  &lt;input name="username" placeholder="Username" required="required" th:field="*{username}"
                         type="text"&gt;
              &lt;/label&gt;
              &lt;ul&gt;
                  &lt;li th:each="err : ${#fields.errors('username')}" th:text="${err}"&gt;&lt;/li&gt;
              &lt;/ul&gt;
              &lt;label&gt;
                  &lt;input name="realName" placeholder="Real Name"
                         type="text" th:field="*{realName}"&gt;
              &lt;/label&gt;
              &lt;ul&gt;
                  &lt;li th:each="err : ${#fields.errors('realName')}" th:text="${err}"&gt;&lt;/li&gt;
              &lt;/ul&gt;
              &lt;span&gt;&lt;/span&gt;&lt;br&gt;
              &lt;label&gt;
                  &lt;input name="email" placeholder="Email" required="required" th:field="*{email}"
                         type="email"&gt;
              &lt;/label&gt;
              &lt;ul&gt;
                  &lt;li th:each="err : ${#fields.errors('email')}" th:text="${err}"&gt;&lt;/li&gt;
              &lt;/ul&gt;
  
              &lt;label&gt;
                  &lt;input name="phoneNumber" placeholder="Phone Number" required="required" th:field="*{phoneNumber}"
                         type="tel"&gt;
              &lt;/label&gt;
              &lt;ul&gt;
                  &lt;li th:each="err : ${#fields.errors('phoneNumber')}" th:text="${err}"&gt;&lt;/li&gt;
              &lt;/ul&gt;
              &lt;span&gt;&lt;/span&gt;&lt;br&gt;
  
              &lt;label&gt;
                  &lt;input name="password" placeholder="Password" th:field="*{password}"
                         required="required" type="password"&gt;
              &lt;/label&gt;
              &lt;ul&gt;
                  &lt;li th:each="err : ${#fields.errors('password')}" th:text="${err}"&gt;&lt;/li&gt;
              &lt;/ul&gt;
              &lt;label&gt;
                  &lt;input name="passwordMatcher" placeholder="Repeat password" th:field="*{matchingPassword}"
                         required="required" type="password"&gt;
              &lt;/label&gt;
              &lt;ul&gt;
                  &lt;li th:each="err : ${#fields.errors('matchingPassword')}" th:text="${err}"&gt;&lt;/li&gt;
              &lt;/ul&gt;
              &lt;span&gt;&lt;/span&gt;&lt;br&gt;
              &lt;button type="submit" style="margin-top: 20px"&gt;Register&lt;/button&gt;
          &lt;/form&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>css fragment</p>
  
  <pre><code>&lt;html lang="en" xmlns:th="http://www.thymeleaf.org" xmlns="http://www.w3.org/1999/html"&gt;
  &lt;div th:fragment="css_background_layer"&gt;
  
      &lt;link href="https://cdnjs.cloudflare.com/ajax/libs/normalize/5.0.0/normalize.min.css"
            rel="stylesheet"
            th:href="@{'https://cdnjs.cloudflare.com/ajax/libs/normalize/5.0.0/normalize.min.css'}"
            type="text/css"&gt;
  
      &lt;link href="css/style.css" rel="stylesheet"
            th:href="@{css/style.css}"
            type="text/css"&gt;
  
      &lt;div class="overlay"&gt;&lt;/div&gt;
  &lt;/div&gt;
  &lt;/html&gt;
  </code></pre>