tighten up callouts and remove backgrounds

docs/_includes/css/tables.html

@@ -349,6 +349,20 @@
 
   <h2 id="tables-responsive">Responsive tables</h2>
   <p>Create responsive tables by wrapping any <code>.table</code> in <code>.table-responsive</code> to make them scroll horizontally on small devices (under 768px). When viewing on anything larger than 768px wide, you will not see any difference in these tables.</p>
+
+  <div class="bs-callout bs-callout-warning">
+    <h4>Firefox and fieldsets</h4>
+    <p>Firefox has some awkward fieldset styling involving <code>width</code> that interferes with the responsive table. This cannot be overriden without a Firefox-specific hack:</p>
+{% highlight css %}
+@-moz-document url-prefix() {
+  fieldset {
+    display: table-cell;
+  }
+}
+{% endhighlight %}
+    <p>For more information, read <a href="http://stackoverflow.com/questions/17408815/fieldset-resizes-wrong-appears-to-have-unremovable-min-width-min-content/17863685#17863685">this Stack Overflow answer</a>.</p>
+  </div>
+
   <div class="bs-example">
     <div class="table-responsive">
       <table class="table">

docs/assets/css/_src/docs.css

@@ -670,9 +670,9 @@ h1[id] {
 
 /* Common styles for all types */
 .bs-callout {
-  padding: 20px;
+  padding: 5px 20px;
   margin: 20px 0;
-  border-left: 3px solid #eee;
+  border-left: 5px solid #eee;
 }
 .bs-callout h4 {
   margin-top: 0;
@@ -686,23 +686,25 @@ h1[id] {
   border-radius: 3px;
 }
 
+/* Tighten up space between multiple callouts */
+.bs-callout + .bs-callout {
+  margin-top: -10px;
+}
+
 /* Variations */
 .bs-callout-danger {
-  background-color: #fdf7f7;
   border-color: #d9534f;
 }
 .bs-callout-danger h4 {
   color: #d9534f;
 }
 .bs-callout-warning {
-  background-color: #fcf8f2;
   border-color: #f0ad4e;
 }
 .bs-callout-warning h4 {
   color: #f0ad4e;
 }
 .bs-callout-info {
-  background-color: #f4f8fa;
   border-color: #5bc0de;
 }
 .bs-callout-info h4 {