chore: polish /content/detail layout -- drop header underline, bigger title, spacing around diagram

Adam's feedback: the teal border-bottom under the entity name read as
a separator that suggested another section was meant to follow it,
when really it was just the page title. Also the download bar and
diagram were jammed against the Overview's Summation text.

All overrides scoped to ::ng-deep cr-description-tab inside the
website's detail card -- the pathway-browser's details panel keeps
the existing compact styling.

  - .header gets `border-bottom: none` and tighter padding/margin;
    name bumps to 28px h1 weight so it reads as the page title.
  - app-detail-download-bar gets a 28px top margin to separate it
    from the Summation row.
  - app-detail-diagram gets a 16px top + 8px bottom margin so it
    breathes between the download bar and the next section divider.

Author: adamjohnwright

projects/website-angular/src/app/content/detail/detail.component.scss

@@ -106,6 +106,37 @@
     background: unset;
   }
 
+  // The pathway-browser's details panel uses a teal underline under the
+  // entity name as a tab separator. On the standalone website detail
+  // page the title is the page header, not a tab, so the underline
+  // reads as visual noise. Drop it and give the name h1 weight to
+  // match other top-level page titles on the site.
+  .header.header {
+    border-bottom: none;
+    padding: 0;
+    margin: 0 0 8px;
+    height: auto;
+    align-items: baseline;
+  }
+  .header.header .name {
+    font-size: 28px;
+    font-weight: 600;
+    line-height: 1.25;
+  }
+
+  // Breathing room around the projected download bar + diagram.
+  // Description-tab puts both inside the Overview slot; on the panel
+  // version they're absent, so we only need to space them on the
+  // standalone page.
+  app-detail-download-bar {
+    display: block;
+    margin: 28px 0 0;
+  }
+  app-detail-diagram {
+    display: block;
+    margin: 16px 0 8px;
+  }
+
   #details {
     .content {
       min-width: 0;