graph_editor: CSS improvements

 - make the gadget full page, this is better when using in an iframe
 - "highlight" the currently hover edge, which makes the graph more readable
 when there are overlapping edges.
 - user helvetica font every where

bt5/erp5_graph_editor/SkinTemplateItem/portal_skins/erp5_graph_editor/dream_graph_editor/jsplumb/jsplumb.css.css

+body {
+    margin: 0px;
+}
+
 .graph_container {
     position: relative;
-    font-size: 80%;
-    border: 1px solid #999;
-
-    min-width: 400px;
-    min-height: 400px;
+    font-size: 0.8em;
+    width: 100vw;
+    height: 100vh;
 
     overflow: hidden;
     background-color: #eaedef;
     text-align: center;
+    font-family: helvetica;
 }
 
 .window,
@@ -22,6 +25,7 @@
     -webkit-box-shadow: 2px 2px 19px #aaa;
     -moz-box-shadow: 2px 2px 19px #aaa
 }
+
 path,
 ._jsPlumb_endpoint {
     cursor: pointer
@@ -42,6 +46,11 @@ path,
 ._jsPlumb_overlay {
     z-index: 23
 }
+._jsPlumb_overlay._jsPlumb_hover {
+    z-index: 25!important;
+    font-size: 1.2em;
+    font-weight: bold;
+}
 ._jsPlumb_connector._jsPlumb_hover {
     z-index: 21!important
 }
@@ -54,8 +63,7 @@ path,
     filter: alpha(opacity=80);
     background-color: #fff;
     color: #000;
-    font-family: helvetica;
-    padding: .5em
+    padding: .5em;
 }
 .window,
 .dummy_window {
@@ -65,12 +73,9 @@ path,
     box-sizing: border-box;
     position: absolute;
     color: #000;
-    font-family: serif;
-    font-style: italic;
     padding-top: .9em;
     font-size: .9em;
     cursor: move;
-    font-size: 11px;
     -webkit-transition: background-color .1s ease-in;
     -moz-transition: background-color .1s ease-in;
     transition: background-color .1s ease-in;
@@ -79,13 +84,15 @@ path,
 .window:hover {
     background-color: #5c96bc;
     background-image: none;
-    color: #fff
+    color: #fff;
+    font-weight: bold;
 }
 .dummy_window {
     position: absolute;
     top: 0;
     left: 0;
-    visibility: hidden
+    visibility: hidden;
+    z-index: -1;
 }
 .ep {
     position: absolute;
@@ -105,8 +112,10 @@ path,
 .dragHover {
     background-color: #1e8151;
     background-image: none;
-    color: #fff
+    color: #fff;
+    font-weight: bold;
 }
+
 path {
     cursor: pointer
 }
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