fix(website): resolve article text colour inside themed scope

Injected markdown inherited color from body, which sits outside the
ThemeProvider and always resolved the light-mode token, making body
copy unreadable in dark mode.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 80686fef-efe3-4cdd-8cd6-bfa61a5d0af6

website/src/components/brand/styles/dotnet-upgrade.module.css

@@ -515,6 +515,11 @@
   display: flex;
   flex-direction: column;
   gap: var(--base-size-16);
+  /* Raw markdown is injected here without Primer Brand components, so it would
+     otherwise inherit `color` from `body` — which sits *outside* the
+     ThemeProvider and therefore always resolves the light-mode token. Setting
+     it here resolves the token inside the themed scope instead. */
+  color: var(--brand-color-text-default);
   /* Large base padding around the text on all sides of the content column. */
   padding: var(--base-size-32);
   /* Section divider — kept inside the left (text) column only, spanning from its

website/src/components/brand/styles/github-copilot-app.module.css

@@ -940,6 +940,11 @@
   display: flex;
   flex-direction: column;
   gap: var(--base-size-16);
+  /* Raw markdown is injected here without Primer Brand components, so it would
+     otherwise inherit `color` from `body` — which sits *outside* the
+     ThemeProvider and therefore always resolves the light-mode token. Setting
+     it here resolves the token inside the themed scope instead. */
+  color: var(--brand-color-text-default);
   padding: var(--base-size-32);
   border-block-start: var(--brand-borderWidth-thin) solid
     var(--brand-color-border-muted);