diff --git a/app/static/config.yml b/app/static/config.yml
index 173bc6b..7e681fe 100644
--- a/app/static/config.yml
+++ b/app/static/config.yml
@@ -2,7 +2,7 @@
 css:
   item:
     - ../static/css/bootstrap.css
-
+    - ../static/css/highlighted.css
 # 全局引入的js文件地址
 js:
   head: # 在页面加载之前加载
diff --git a/app/static/css/highlighted.css b/app/static/css/highlighted.css
new file mode 100644
index 0000000..167f595
--- /dev/null
+++ b/app/static/css/highlighted.css
@@ -0,0 +1,5 @@
+
+.highlighted {
+    color: red;
+    font-weight: normal;
+}
\ No newline at end of file
diff --git a/app/static/js/highlight.js b/app/static/js/highlight.js
index d75dace..245931e 100644
--- a/app/static/js/highlight.js
+++ b/app/static/js/highlight.js
@@ -69,11 +69,12 @@ function highLight() {
     // 删除所有的mark标签,防止标签发生嵌套
     articleContent = articleContent.replace(/<(mark)[^>]*>/gi, "");
     articleContent = articleContent.replace(/<(\/mark)[^>]*>/gi, "");
-    // 将文章中所有出现该单词word的地方改为："<mark>" + word + "<mark>"。
+    // 将文章中所有出现该单词word的地方改为："<span class='highlighted'>" + word + "</span>"。
     for (let word of totalSet) {
-        articleContent = articleContent.replace(new RegExp("\\b" + word + "\\b", "g"), "<mark>" + word + "</mark>");
+        articleContent = articleContent.replace(new RegExp("\\b" + word + "\\b", "g"), "<span class='highlighted'>" + word + "</span>");
     }
     document.getElementById("article").innerHTML = articleContent;
+
 }
 
 function cancelHighlighting() {
diff --git a/app/test/test_bug551_DingZeYu.py b/app/test/test_bug551_DingZeYu.py
new file mode 100644
index 0000000..015fb5a
--- /dev/null
+++ b/app/test/test_bug551_DingZeYu.py
@@ -0,0 +1,37 @@
+import time
+import pytest
+from selenium import webdriver
+from selenium.webdriver import ActionChains
+from selenium.webdriver.common.by import By
+from selenium.webdriver.common.alert import Alert
+from selenium.webdriver.support import expected_conditions as EC
+from selenium.webdriver.support.wait import WebDriverWait
+from helper import signup
+
+def test_bug551(driver, URL):
+    driver.maximize_window()
+    driver.get(URL)
+
+    username, password = signup(URL, driver)
+
+    article = driver.find_element(By.ID, 'article')
+    actions = ActionChains(driver)
+
+    actions.move_to_element(article)
+    actions.click_and_hold()
+    actions.move_by_offset(450, 200)
+    actions.release()
+    actions.perform()
+
+    # 获取选中高亮部分的单词的元素
+    highlighted_words = driver.find_elements(By.CLASS_NAME, 'highlighted')
+
+    # 验证选中部分的单词是否同时应用了需求样式
+    expected_font_weight = "400"  
+
+    for word in highlighted_words:
+        font_weight = word.value_of_css_property("font-weight")
+        assert font_weight == expected_font_weight, f"选中部分的单词的字体样式错误"
+
+    time.sleep(5)
+    driver.quit()