Small CSS changes

* Removed opacity change on hover.
* Removed default opacity.
* Remove default button color.
* Added opacity change on button disable.

debug/simplemde.css

@@ -382,7 +382,6 @@ span.CodeMirror-selectedtext { background: none; }
 
 .editor-toolbar {
     position: relative;
-    opacity: .6;
     -webkit-user-select: none;
     -moz-user-select: none;
     -ms-user-select: none;
@@ -411,12 +410,6 @@ span.CodeMirror-selectedtext { background: none; }
     margin-top: 8px
 }
 
-.editor-toolbar:hover,
-.editor-wrapper input.title:focus,
-.editor-wrapper input.title:hover {
-    opacity: .8
-}
-
 .editor-toolbar.fullscreen {
     width: 100%;
     height: 50px;
@@ -473,7 +466,6 @@ span.CodeMirror-selectedtext { background: none; }
     display: inline-block;
     text-align: center;
     text-decoration: none!important;
-    color: #2c3e50!important;
     width: 30px;
     height: 30px;
     margin: 0;
@@ -534,11 +526,9 @@ span.CodeMirror-selectedtext { background: none; }
     content: "▼";
 }
 
-.editor-toolbar.disabled-for-preview a:not(.no-disable) {
+.editor-toolbar.disabled-for-preview button:not(.no-disable) {
+    opacity: .6;
     pointer-events: none;
-    background: #fff;
-    border-color: transparent;
-    text-shadow: inherit;
 }
 
 @media only screen and (max-width: 700px) {

src/css/simplemde.css

@@ -29,7 +29,6 @@
 
 .editor-toolbar {
     position: relative;
-    opacity: .6;
     -webkit-user-select: none;
     -moz-user-select: none;
     -ms-user-select: none;
@@ -58,12 +57,6 @@
     margin-top: 8px
 }
 
-.editor-toolbar:hover,
-.editor-wrapper input.title:focus,
-.editor-wrapper input.title:hover {
-    opacity: .8
-}
-
 .editor-toolbar.fullscreen {
     width: 100%;
     height: 50px;
@@ -120,7 +113,6 @@
     display: inline-block;
     text-align: center;
     text-decoration: none!important;
-    color: #2c3e50!important;
     width: 30px;
     height: 30px;
     margin: 0;
@@ -181,11 +173,9 @@
     content: "▼";
 }
 
-.editor-toolbar.disabled-for-preview a:not(.no-disable) {
+.editor-toolbar.disabled-for-preview button:not(.no-disable) {
+    opacity: .6;
     pointer-events: none;
-    background: #fff;
-    border-color: transparent;
-    text-shadow: inherit;
 }
 
 @media only screen and (max-width: 700px) {