Update link styling to darker gray-blue and remove default underline

Author: bhouston

src/css/custom.css

@@ -15,7 +15,7 @@
   --ifm-color-primary-lightest: #0e85ff;
   --ifm-code-font-size: 95%;
   --docusaurus-highlighted-code-line-bg: rgba(0, 0, 0, 0.1);
-  --ifm-link-color: #0066cc;
-  --ifm-link-hover-color: #0057ad;
-  --ifm-link-decoration: underline;
+  --ifm-link-color: #3a5978; /* Darker gray-blue */
+  --ifm-link-hover-color: #2c4359; /* Even darker on hover */
+  --ifm-link-decoration: none; /* Remove default underline */
 }