Use a CSS snippet instead of the style settings plugin

appearance.json

@@ -7,7 +7,8 @@
   "baseFontSize": 18,
   "enabledCssSnippets": [
     "font",
-    "vim-cursor"
+    "vim-cursor",
+    "text-normalize"
   ],
   "accentColor": ""
 }

community-plugins.json

@@ -5,6 +5,5 @@
   "multi-vault-links",
   "typewriter-mode",
   "obsidian-vimrc-support",
-  "tag-wrangler",
-  "obsidian-style-settings"
+  "tag-wrangler"
 ]

snippets/text-normalize.css

@@ -0,0 +1,16 @@
+/* Minimal -- heading overrides */
+body {
+  --h1-size: 18px;
+  --h1-weight: 600;
+  --h2-size: 18px;
+  --h2-weight: 600;
+  --h3-size: 18px;
+  --h3-weight: 600;
+  --h4-size: 18px;
+  --h4-weight: 600;
+  --h5-size: 18px;
+  --h5-weight: 600;
+  --h6-size: 18px;
+  --h6-weight: 600;
+  --h6-variant: normal;
+}