fixed y-alignment for north/south ports

src/elements/element.typ

@@ -88,16 +88,27 @@
     if to-side in ports-margins {
       margins = ports-margins.at(to-side)
     }
+
+    let dy
+    let top-margin
+    if to-side in ("east", "west") {
       let used-pct = 100% - margins.at(0) - margins.at(1)
       let used-height = height * used-pct / 100%
-    let top-margin = height * margins.at(0) / 100%
+      top-margin = height * margins.at(0) / 100%
       
-    let dy = used-height * (i + 1) / (ports.at(to-side).len() + 1)
+      dy = used-height * (i + 1) / (ports.at(to-side).len() + 1)
 
       if not auto-ports {
         top-margin = 0
         dy = ports-y.at(to)(height)
       }
+    } else if to-side == "north" {
+      dy = 0
+      top-margin = 0
+    } else if to-side == "south" {
+      dy = height
+      top-margin = 0
+    }
     
     let (ctx, from-pos) = coordinate.resolve(ctx, from)
     y = from-pos.at(1) + dy - height + top-margin