[opt] gist darkmode textcolor (#445)

source/css/_common/highlight.styl

@@ -75,7 +75,6 @@ p>code:not([class]),li>code:not([class])
     padding-left: 0.25em
 
 .md-text .gist 
-  --fgColor-default: var(--text-p1)
   .gist-file 
     border: 1px solid var(--block-border)
     border-radius: $border-card
@@ -86,9 +85,12 @@ p>code:not([class]),li>code:not([class])
     display: inherit
     border: none
     border-radius: 0
-    background: none
+    background: var(--block)
     margin: 0
     padding: 1em 0
+  .blob-code-inner
+    color: var(--text-p1)
+    font-family: $ff-codeblock
   .gist-meta
     background: var(--block-border)