Update

src/data.js

@@ -67,7 +67,7 @@ export const items = [
     },
     {
         icon: 'UnskilledLabour2.svg',
-        linkable: ['Gefährdete Gesundheit'],
+        linkable: ['Gefährdete Gesundheit', 'Überarbeitet', 'Arm'],
         img: 'hans.png',
         name: 'Hans',
         desc: '12, Kinderarbeiter',

src/display.js

@@ -19,6 +19,7 @@ export class Display {
     target.addEventListener('dragstart', e => {
       let target = findA(e.target)
       if (!target || !target.draggable) return
+      e.dataTransfer.clearData()
       e.dataTransfer.setData('application/prs.x', target.dataset['id'])
       e.dataTransfer.effectAllowed = 'link'
     })

src/index.js

@@ -24,6 +24,9 @@ class Actions {
     state.show = null
   }
   link(from, to) {
+    if (from == to) return false
+    const ok = state.items[from].linkable.filter(i => state.items[to].linkable.includes(i)).length > 0
+    if (!ok) return false
     state.links.push({id: state.links.length, from, to})
     return true
   }

style.css

@@ -62,7 +62,7 @@ body {
   text-align: center;
   position: absolute;
   transform-origin: 0 0;
-  font-size: 1.2em;
+  font-size: 1.4em;
   padding: 0 70px;
   box-sizing: border-box;
 }