try to have buttons render properly on nbviewer

examples/notebooks/Part 1 - Running Code.ipynb

@@ -45,7 +45,7 b''
       "};\n",
       "</script>\n",
       "\n",
-      "Run a code cell using `Shift-Enter` or pressing the <button><i class=\"icon-play\" /></button> button in the <a href=\"#\" onMouseover=\"hl('#maintoolbar-container', 1)\" onMouseout=\"hl('#maintoolbar-container', 0)\">toolbar</a> above:"
+      "Run a code cell using `Shift-Enter` or pressing the <button><i class=\"icon-play\"></i></button> button in the <a href=\"#\" onMouseover=\"hl('#maintoolbar-container', 1)\" onMouseout=\"hl('#maintoolbar-container', 0)\">toolbar</a> above:"
      ]
     },
     {
@@ -90,7 +90,7 b''
      "cell_type": "markdown",
      "metadata": {},
      "source": [
-      "Code is run in a separate process called the IPython Kernel.  The Kernel can be interrupted or restarted.  Try running the following cell and then hit the <button><i class='icon-stop'/></button> button in the <a href=\"#\" onMouseover=\"hl('#maintoolbar-container', 1)\" onMouseout=\"hl('#maintoolbar-container', 0)\">toolbar</a> above."
+      "Code is run in a separate process called the IPython Kernel.  The Kernel can be interrupted or restarted.  Try running the following cell and then hit the <button><i class='icon-stop'></i></button> button in the <a href=\"#\" onMouseover=\"hl('#maintoolbar-container', 1)\" onMouseout=\"hl('#maintoolbar-container', 0)\">toolbar</a> above."
      ]
     },
     {