limit the size of rendered images

www/slide/index.html

@@ -81,7 +81,12 @@
         #content ol {
             font-size: 26px;
         }
-
+        #content img {
+            position: relative;
+            max-width: 90%;
+            max-height: 90%;
+            margin: auto;
+        }
     </style>
 </head>
 <body>