각주 버그 수정

https://github.com/openNAMU/openNAMU/issues/2122

views/main_css/css/main.css

@@ -264,6 +264,7 @@ code, pre {
     padding: 10px;
 
     background-color: #efefef;
+    color: initial;
     
     border: 1px solid #cecece;
 

views/main_css/css/sub/dark.css

@@ -68,6 +68,7 @@ blockquote {
 
 .opennamu_popup_footnote {
     background-color: #313236;
+    color: white;
 }
 
 .opennamu_history_blind {