feat: add custom css

Author: yanglbme

docs-en/stylesheets/extra.css

@@ -11,7 +11,7 @@ tags:
 edit_url: "https://github.com/doocs/leetcode/edit/main/solution/0000-0099/0001.Two%20Sum/README.md"
 ---
 
-# [1. 两数之和](https://leetcode.cn/problems/two-sum) :unlock:
+# [1. 两数之和](https://leetcode.cn/problems/two-sum)
 
 ## 题目描述
 

docs/lc/1.md

@@ -112,6 +112,7 @@ extra_javascript:
   - https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.16.7/contrib/auto-render.min.js
 
 extra_css:
+  - stylesheets/extra.css
   - https://cdnjs.cloudflare.com/ajax/libs/KaTeX/0.16.7/katex.min.css
 
 extra: