fix broken buttons on css docs

docs/css.html

@@ -1020,7 +1020,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
             <input type="checkbox"> Check me out
           </label>
         </div>
-        <button type="submit" class="btn">Submit</button>
+        <button type="submit" class="btn btn-default">Submit</button>
       </fieldset>
     </form><!-- /example -->
 {% highlight html %}
@@ -1035,7 +1035,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
         <input type="checkbox"> Check me out
       </label>
     </div>
-    <button type="submit" class="btn">Submit</button>
+    <button type="submit" class="btn btn-default">Submit</button>
   </fieldset>
 </form>
 {% endhighlight %}
@@ -1058,7 +1058,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
           <input type="checkbox"> Remember me
         </label>
       </div>
-      <button type="submit" class="btn">Sign in</button>
+      <button type="submit" class="btn btn-default">Sign in</button>
     </form><!-- /example -->
 {% highlight html %}
 <form class="form-inline">
@@ -1069,7 +1069,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
       <input type="checkbox"> Remember me
     </label>
   </div>
-  <button type="submit" class="btn">Sign in</button>
+  <button type="submit" class="btn btn-default">Sign in</button>
 </form>
 {% endhighlight %}
 
@@ -1101,7 +1101,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
       </div>
       <div class="control-group">
         <div class="controls">
-          <button type="submit" class="btn">Sign in</button>
+          <button type="submit" class="btn btn-default">Sign in</button>
         </div>
       </div>
     </form>
@@ -1126,7 +1126,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
   </div>
   <div class="control-group">
     <div class="controls">
-      <button type="submit" class="btn">Sign in</button>
+      <button type="submit" class="btn btn-default">Sign in</button>
     </div>
   </div>
 </form>
@@ -1303,7 +1303,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
 
     <div class="bs-callout">
       <h4>Link functionality of <code>&lt;a&gt;</code> not impacted</h4>
-      <p>This class will only change the appearance of <code>&lt;a class="btn"&gt;</code> buttons, not their functionality. Use custom JavaScript to disable links here.</p>
+      <p>This class will only change the appearance of <code>&lt;a class="btn btn-default"&gt;</code> buttons, not their functionality. Use custom JavaScript to disable links here.</p>
     </div>
 
     <div class="bs-callout">
@@ -1487,7 +1487,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
     <form class="bs-example">
       <div class="input-group col col-lg-7">
         <span class="input-group-btn">
-          <button class="btn" type="button">Go!</button>
+          <button class="btn btn-default" type="button">Go!</button>
         </span>
         <input type="text">
       </div>
@@ -1495,14 +1495,14 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
       <div class="input-group col col-lg-7">
         <input type="text">
         <span class="input-group-btn">
-          <button class="btn" type="button">Go!</button>
+          <button class="btn btn-default" type="button">Go!</button>
         </span>
       </div>
     </form>
 {% highlight html %}
 <div class="input-group col col-lg-7">
   <span class="input-group-btn">
-    <button class="btn" type="button">Go!</button>
+    <button class="btn btn-default" type="button">Go!</button>
   </span>
   <input type="text">
 </div>
@@ -1510,7 +1510,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
 <div class="input-group col col-lg-7">
   <input type="text">
   <span class="input-group-btn">
-    <button class="btn" type="button">Go!</button>
+    <button class="btn btn-default" type="button">Go!</button>
   </span>
 </div>
 {% endhighlight %}
@@ -1520,7 +1520,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
     <form class="bs-example">
       <div class="input-group col col-lg-7">
         <div class="input-group-btn">
-          <button class="btn dropdown-toggle" data-toggle="dropdown">Action <span class="caret"></span></button>
+          <button class="btn btn-default dropdown-toggle" data-toggle="dropdown">Action <span class="caret"></span></button>
           <ul class="dropdown-menu">
             <li><a href="#">Action</a></li>
             <li><a href="#">Another action</a></li>
@@ -1535,7 +1535,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
       <div class="input-group col col-lg-7">
         <input type="text">
         <div class="input-group-btn">
-          <button class="btn dropdown-toggle" data-toggle="dropdown">Action <span class="caret"></span></button>
+          <button class="btn btn-default dropdown-toggle" data-toggle="dropdown">Action <span class="caret"></span></button>
           <ul class="dropdown-menu">
             <li><a href="#">Action</a></li>
             <li><a href="#">Another action</a></li>
@@ -1549,7 +1549,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
 {% highlight html %}
 <div class="input-group col col-lg-7">
   <div class="input-group-btn">
-    <button class="btn dropdown-toggle" data-toggle="dropdown">Action <span class="caret"></span></button>
+    <button class="btn btn-default dropdown-toggle" data-toggle="dropdown">Action <span class="caret"></span></button>
     <ul class="dropdown-menu">
       <li><a href="#">Action</a></li>
       <li><a href="#">Another action</a></li>
@@ -1564,7 +1564,7 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
 <div class="input-group col col-lg-7">
   <input type="text">
   <div class="input-group-btn">
-    <button class="btn dropdown-toggle" data-toggle="dropdown">Action <span class="caret"></span></button>
+    <button class="btn btn-default dropdown-toggle" data-toggle="dropdown">Action <span class="caret"></span></button>
     <ul class="dropdown-menu">
       <li><a href="#">Action</a></li>
       <li><a href="#">Another action</a></li>
@@ -1580,8 +1580,8 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
     <form class="bs-example">
       <div class="input-group col col-lg-7">
         <div class="input-group-btn">
-          <button class="btn" tabindex="-1">Action</button>
-          <button class="btn dropdown-toggle" data-toggle="dropdown" tabindex="-1">
+          <button class="btn btn-default" tabindex="-1">Action</button>
+          <button class="btn btn-default dropdown-toggle" data-toggle="dropdown" tabindex="-1">
             <span class="caret"></span>
           </button>
           <ul class="dropdown-menu">
@@ -1600,8 +1600,8 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
       <div class="input-group col col-lg-7">
         <input type="text">
         <div class="input-group-btn">
-          <button class="btn" tabindex="-1">Action</button>
-          <button class="btn dropdown-toggle" data-toggle="dropdown" tabindex="-1">
+          <button class="btn btn-default" tabindex="-1">Action</button>
+          <button class="btn btn-default dropdown-toggle" data-toggle="dropdown" tabindex="-1">
             <span class="caret"></span>
           </button>
           <ul class="dropdown-menu">
@@ -1682,13 +1682,13 @@ For example, <code>&lt;section&gt;</code> should be wrapped as inline.
     <form class="bs-example">
       <div class="form-actions">
         <button type="submit" class="btn btn-primary">Save changes</button>
-        <button type="button" class="btn">Cancel</button>
+        <button type="button" class="btn btn-default">Cancel</button>
       </div>
     </form>
 {% highlight html %}
 <div class="form-actions">
   <button type="submit" class="btn btn-primary">Save changes</button>
-  <button type="button" class="btn">Cancel</button>
+  <button type="button" class="btn btn-default">Cancel</button>
 </div>
 {% endhighlight %}