fix: Fixed font color for education pages in dark mode (#943)

assets/styles/components/texts.scss

@@ -72,7 +72,8 @@ html[data-theme='dark'] {
   h2,
   h3,
   h4,
-  h5 {
+  h5,
+  h6 {
     color: get-dark-color('heading-color');
   }
 

assets/styles/sections/education.scss

@@ -229,6 +229,11 @@ html[data-theme='dark'] {
               border-left: 2px solid get-dark-color('accent-color');
             }
           }
+          .custom-section {
+            .custom-content {
+              color: get-dark-color('text-color');
+            }
+          }
         }
       }
     }