Demo button

README.md

@@ -37,8 +37,10 @@ Please cite the following paper when using this extension:
 U. Dogrusoz , A. Karacelik, I. Safarli, H. Balci, L. Dervishi, and M.C. Siper, "[Efficient methods and readily customizable libraries for managing complexity of large networks](https://doi.org/10.1371/journal.pone.0197238)", PLoS ONE, 13(5): e0197238, 2018.
 
 ## Demo
-
-Click [here](https://ivis-at-bilkent.github.io/cytoscape.js-grid-guide/demo.html) for demo
+Here is a demo:
+<p align="center">
+<a href="https://ivis-at-bilkent.github.io/cytoscape.js-grid-guide/demo.html"><img src="https://www.cs.bilkent.edu.tr/~ivis/images/demo1.png" height=42px></a>
+</p>
 
 ## API