Centre one 42rem reading column on content, post, event and FAQ pages

Elternbeirat.Web/wwwroot/app.css

@@ -1050,13 +1050,17 @@ main:focus {
    a normal heading; every group is a block of its own. One raster for all of them,
    so the cards line up across groups: a group of one person gets the same card
    width as a group of six, not a stretched one. 17rem fits a long double name.
+   Like every other block it stays in the 42rem reading column, so the cards share
+   the edges of the text above and below them; that leaves room for two columns
+   (three would need 52.5rem), one on a phone.
    The cards of a row share one height (the grid's default stretch), so a row reads
    as a calm band; the card itself keeps its content at the top (align-content). */
 .markdown-body .team > ul {
     display: grid;
     grid-template-columns: repeat(auto-fill, minmax(17rem, 1fr));
     gap: var(--space-3);
-    max-width: none;
+    box-sizing: border-box;
+    max-width: 42rem;
     margin: 0 0 var(--space-4);
     padding: 0;
     list-style: none;