diff --git a/judge/jinja2/markdown/__init__.py b/judge/jinja2/markdown/__init__.py
index b91679c..3387ddf 100644
--- a/judge/jinja2/markdown/__init__.py
+++ b/judge/jinja2/markdown/__init__.py
@@ -20,14 +20,13 @@ logger = logging.getLogger("judge.html")
 
 NOFOLLOW_WHITELIST = settings.NOFOLLOW_EXCLUDED
 
+
 class CodeSafeInlineGrammar(mistune.InlineGrammar):
     double_emphasis = re.compile(r"^\*{2}([\s\S]+?)()\*{2}(?!\*)")  # **word**
     emphasis = re.compile(r"^\*((?:\*\*|[^\*])+?)()\*(?!\*)")  # *word*
 
 
-class AwesomeInlineGrammar(
-    MathInlineGrammar, CodeSafeInlineGrammar
-):
+class AwesomeInlineGrammar(MathInlineGrammar, CodeSafeInlineGrammar):
     pass
 
 
@@ -126,9 +125,11 @@ class AwesomeRenderer(MathRenderer, mistune.Renderer):
 def create_spoiler(value, style):
     respoiler = re.compile(r"(^\|\|(.+)\s+([\s\S]+?)\s*\|\|)", re.MULTILINE)
     matches = re.findall(respoiler, value)
-    html = "<details><summary style=\"color: brown\">" \
-         + "<span class=\"spoiler-summary\">{summary}</span>" \
-         + "</summary>{detail}</details>"
+    html = (
+        '<details><summary style="color: brown">'
+        + '<span class="spoiler-summary">{summary}</span>'
+        + "</summary>{detail}</details>"
+    )
 
     for entire, summary, detail in matches:
         detail = markdown(detail, style)
@@ -136,6 +137,7 @@ def create_spoiler(value, style):
         value = value.replace(entire, new_html)
     return value
 
+
 @registry.filter
 def markdown(value, style, math_engine=None, lazy_load=False, hard_wrap=False):
     styles = settings.MARKDOWN_STYLES.get(style, settings.MARKDOWN_DEFAULT_STYLE)
diff --git a/judge/jinja2/markdown/math.py b/judge/jinja2/markdown/math.py
index dcde0d1..96e2878 100644
--- a/judge/jinja2/markdown/math.py
+++ b/judge/jinja2/markdown/math.py
@@ -65,5 +65,5 @@ class MathRenderer(mistune.Renderer):
 
     def math(self, math):
         if self.mathoid is None or not math:
-            return r"$%s$" % mistune.escape(str(math))
+            return r"~%s~" % mistune.escape(str(math))
         return self.mathoid.inline_math(math)