Updated obsolete screenshots

gallery.html

@@ -57,7 +57,7 @@
             <p>GPXSee on Windows 10</p>
           </li><li>
             <a href="gallery/mac.png">
-              <img src="gallery/mac_prev.png" width="200" height="280" alt=""/>
+              <img src="gallery/mac_prev.png" width="200" height="261" alt=""/>
             </a>  
             <h3>Mac OS&nbsp;X</h3>
             <p>GPXSee on OS&nbsp;X</p>
@@ -87,7 +87,7 @@
             <p>GPXSee showing a POI file on Windows 10</p>
           </li><li>
             <a href="gallery/lin2.png">
-              <img src="gallery/lin2_prev.png" width="200" height="276" alt=""/>
+              <img src="gallery/lin2_prev.png" width="200" height="265" alt=""/>
             </a>
             <h3>Waypoints</h3>
             <p>GPXSee showing a POI file on Linux</p>
@@ -111,7 +111,7 @@
             <p>GPXSee showing areas (polygons)</p>
           </li><li>
             <a href="gallery/exif.png">
-              <img src="gallery/exif_prev.png" width="200" height="264" alt=""/>
+              <img src="gallery/exif_prev.png" width="200" height="263" alt=""/>
             </a>
             <h3>Geotagged images</h3>
             <p>GPXSee showing geotagged JPEGs</p>