diff --git a/frontend/src/components/document-preview.vue b/frontend/src/components/document-preview.vue
index a3c86309..6892f009 100644
--- a/frontend/src/components/document-preview.vue
+++ b/frontend/src/components/document-preview.vue
@@ -834,3 +834,90 @@ onUnmounted(() => {
   }
 }
 </style>
+
+<!-- highlight.js github.css is a light theme imported globally; its token
+     colors (notably the base #24292e) become unreadable on the dark
+     container background used in dark mode. Remap the palette to the
+     github-dark colors when dark mode is active. Non-scoped on purpose so
+     it covers every hljs block (txt/code preview, markdown code fences). -->
+<style lang="less">
+html[theme-mode="dark"] {
+  .hljs {
+    color: #c9d1d9;
+    background: transparent;
+  }
+  .hljs-doctag,
+  .hljs-keyword,
+  .hljs-meta .hljs-keyword,
+  .hljs-template-tag,
+  .hljs-template-variable,
+  .hljs-type,
+  .hljs-variable.language_ {
+    color: #ff7b72;
+  }
+  .hljs-title,
+  .hljs-title.class_,
+  .hljs-title.class_.inherited__,
+  .hljs-title.function_ {
+    color: #d2a8ff;
+  }
+  .hljs-attr,
+  .hljs-attribute,
+  .hljs-literal,
+  .hljs-meta,
+  .hljs-number,
+  .hljs-operator,
+  .hljs-variable,
+  .hljs-selector-attr,
+  .hljs-selector-class,
+  .hljs-selector-id {
+    color: #79c0ff;
+  }
+  .hljs-regexp,
+  .hljs-string,
+  .hljs-meta .hljs-string {
+    color: #a5d6ff;
+  }
+  .hljs-built_in,
+  .hljs-symbol {
+    color: #ffa657;
+  }
+  .hljs-comment,
+  .hljs-code,
+  .hljs-formula {
+    color: #8b949e;
+  }
+  .hljs-name,
+  .hljs-quote,
+  .hljs-selector-tag,
+  .hljs-selector-pseudo {
+    color: #7ee787;
+  }
+  .hljs-subst {
+    color: #c9d1d9;
+  }
+  .hljs-section {
+    color: #1f6feb;
+    font-weight: bold;
+  }
+  .hljs-bullet {
+    color: #f2cc60;
+  }
+  .hljs-emphasis {
+    color: #c9d1d9;
+    font-style: italic;
+  }
+  .hljs-strong {
+    color: #c9d1d9;
+    font-weight: bold;
+  }
+  .hljs-addition {
+    color: #aff5b4;
+    background-color: #033a16;
+  }
+  .hljs-deletion {
+    color: #ffdcd7;
+    background-color: #67060c;
+  }
+}
+</style>