Addressing accessibility issues with using links instead of buttons.

src/css/simplemde.css

@@ -112,7 +112,9 @@
     padding: 0;
 }
 
-.editor-toolbar a {
+.editor-toolbar a,
+.editor-toolbar button {
+    background: transparent;
     display: inline-block;
     text-align: center;
     text-decoration: none!important;
@@ -120,18 +122,22 @@
     width: 30px;
     height: 30px;
     margin: 0;
+    padding: 0;
     border: 1px solid transparent;
     border-radius: 3px;
     cursor: pointer;
 }
 
 .editor-toolbar a.active,
-.editor-toolbar a:hover {
+.editor-toolbar a:hover,
+.editor-toolbar button.active,
+.editor-toolbar button:hover {
     background: #fcfcfc;
     border-color: #95a5a6;
 }
 
-.editor-toolbar a:before {
+.editor-toolbar a:before,
+.editor-toolbar button:before {
     line-height: 30px
 }
 

src/js/simplemde.js

@@ -96,7 +96,7 @@ function fixShortcut(name) {
  */
 function createIcon(options, enableTooltips, shortcuts) {
 	options = options || {};
-	var el = document.createElement("a");
+	var el = document.createElement("button");
 	enableTooltips = (enableTooltips == undefined) ? true : enableTooltips;
 
 	if(options.title && enableTooltips) {