Fixed image popup margin in rare cases

boards/static/js/image.js

@@ -23,6 +23,8 b''
  for the JavaScript code in this page.
  */
 
+var IMAGE_POPUP_MARGIN = 10;
+
 
 var IMAGE_VIEWERS = [
     ['simple', new SimpleImageViewer()],
@@ -69,8 +71,6 b' SimpleImageViewer.prototype.view = funct'
 
 function PopupImageViewer() {}
 PopupImageViewer.prototype.view = function (post) {
-    var margin = 20; //..change
-
     var el = post;
     var thumb_id = 'full' + el.find('img').attr('alt');
 
@@ -89,11 +89,15 b' PopupImageViewer.prototype.view = functi'
         // New image size
         var w_scale = 1;
         var h_scale = 1;
-        if (full_img_w > win_w) {
-            w_scale = full_img_w / (win_w - margin);
+
+        var freeWidth = win_w - 2 * IMAGE_POPUP_MARGIN;
+        var freeHeight = win_h - 2 * IMAGE_POPUP_MARGIN;
+
+        if (full_img_w > freeWidth) {
+            w_scale = full_img_w / freeWidth;
         }
-        if (full_img_h > win_h) {
-            h_scale = full_img_h / (win_h - margin);
+        if (full_img_h > freeHeight) {
+            h_scale = full_img_h / freeHeight;
         }
 
         var scale = Math.max(w_scale, h_scale)