margins to separate some cards in examples

docs/components/card.md

@@ -331,7 +331,7 @@ Cards include a few options for working with images. Choose from appending "imag
 Similar to headers and footers, cards can include top and bottom "image caps"—images at the top or bottom of a card.
 
 {% example html %}
-<div class="card">
+<div class="card mb-3">
   <img class="card-img-top" data-src="holder.js/100px180/" alt="Card image cap">
   <div class="card-block">
     <h4 class="card-title">Card title</h4>
@@ -389,7 +389,7 @@ You can also use `.card-inverse` with the [contextual backgrounds variants](#bac
 Cards include their own variant classes for quickly changing the `background-color` and `border-color` of a card. **Darker colors require the use of `.card-inverse`.**
 
 {% example html %}
-<div class="card card-inverse card-primary text-center">
+<div class="card card-inverse card-primary mb-3 text-center">
   <div class="card-block">
     <blockquote class="card-blockquote">
       <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
@@ -397,7 +397,7 @@ Cards include their own variant classes for quickly changing the `background-col
     </blockquote>
   </div>
 </div>
-<div class="card card-inverse card-success text-center">
+<div class="card card-inverse card-success mb-3 text-center">
   <div class="card-block">
     <blockquote class="card-blockquote">
       <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
@@ -405,7 +405,7 @@ Cards include their own variant classes for quickly changing the `background-col
     </blockquote>
   </div>
 </div>
-<div class="card card-inverse card-info text-center">
+<div class="card card-inverse card-info mb-3 text-center">
   <div class="card-block">
     <blockquote class="card-blockquote">
       <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
@@ -413,7 +413,7 @@ Cards include their own variant classes for quickly changing the `background-col
     </blockquote>
   </div>
 </div>
-<div class="card card-inverse card-warning text-center">
+<div class="card card-inverse card-warning mb-3 text-center">
   <div class="card-block">
     <blockquote class="card-blockquote">
       <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
@@ -439,7 +439,7 @@ Cards include their own variant classes for quickly changing the `background-col
 In need of a colored card, but not the hefty background colors they bring? Replace the default modifier classes with the `.card-outline-*` ones to style just the `border-color` of a card.
 
 {% example html %}
-<div class="card card-outline-primary text-center">
+<div class="card card-outline-primary mb-3 text-center">
   <div class="card-block">
     <blockquote class="card-blockquote">
       <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
@@ -447,7 +447,7 @@ In need of a colored card, but not the hefty background colors they bring? Repla
     </blockquote>
   </div>
 </div>
-<div class="card card-outline-secondary text-center">
+<div class="card card-outline-secondary mb-3 text-center">
   <div class="card-block">
     <blockquote class="card-blockquote">
       <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
@@ -455,7 +455,7 @@ In need of a colored card, but not the hefty background colors they bring? Repla
     </blockquote>
   </div>
 </div>
-<div class="card card-outline-success text-center">
+<div class="card card-outline-success mb-3 text-center">
   <div class="card-block">
     <blockquote class="card-blockquote">
       <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
@@ -463,7 +463,7 @@ In need of a colored card, but not the hefty background colors they bring? Repla
     </blockquote>
   </div>
 </div>
-<div class="card card-outline-info text-center">
+<div class="card card-outline-info mb-3 text-center">
   <div class="card-block">
     <blockquote class="card-blockquote">
       <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>
@@ -471,7 +471,7 @@ In need of a colored card, but not the hefty background colors they bring? Repla
     </blockquote>
   </div>
 </div>
-<div class="card card-outline-warning text-center">
+<div class="card card-outline-warning mb-3 text-center">
   <div class="card-block">
     <blockquote class="card-blockquote">
       <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer posuere erat a ante.</p>