Adjust tag window to content

Before this change, if many "Similar tags by other users" are displayed, window position would bleed

canvas/css/canvas.css

@@ -525,8 +525,13 @@ div#move-window ul {
 ----------------------------------------------- */
 
 div#tag-window {
-    left: 12.5%;
     width: 75%;
+    max-height: 80%;
+    overflow: scroll;
+    /* Center window horizontally and vertically */
+    top: 50%;
+    left: 50%;
+    transform: translate(-50%, -50%);    
 }
 /*
 div#tag-window h2#tag-description {