fix scrolldown height for permalinks

wiki/README.md

@@ -23,6 +23,12 @@ cp template.md my-new-page.md
 
 * edit as needed!
 
+* test your changes with a local php server
+```sh
+composer install
+php -S localhost:9000
+```
+
 * commit your changes and [create a pull request](https://tildegit.org/team/site/pulls) :)
 ```sh
 git add --all

wiki/index.php

@@ -6,8 +6,8 @@ $additional_head = "
     :target:before {
         content:\"\";
         display:block;
-        height:90px; /* fixed header height*/
-        margin:-90px 0 0; /* negative fixed header height */
+        height:50px; /* fixed header height*/
+        margin:-50px 0 0; /* negative fixed header height */
     }
     </style>
     <meta property='og:type' content='website'>