Merge pull request #345 from maxim-belkin/margin0

Code/callout/prereq/etc blocks: set left and right margins to 0

diff --combined assets/css/lesson.scss
index 0e0ab1e180d258ed53731495e5f308f7034cece8,20d1cde239ca5cbd3248d79585924d131ec028ac..522e4fde6b0aa1910a54053926d6ef220f064e7e
--- 1/assets/css/lesson.scss
--- 2/assets/css/lesson.scss
+++ b/assets/css/lesson.scss
@@@ -31,7 -31,7 +31,7 @@@ $color-testimonial: #fc8dc1 !default
  @mixin cdSetup($color) {
      color: $color;
      border-left: solid 5px $color;
-     margin: 15px;
+     margin: 15px 0;
      border-radius: 4px 0 0 4px;
  }
  
@@@ -84,7 -84,7 +84,7 @@@ $codeblock-padding: 5px !default
    border-radius: 4px;
    padding-bottom: $codeblock-padding;
  
-   margin: 15px;
+   margin: 15px 0;
  
    h2 {
      padding-top: $codeblock-padding;
@@@ -163,8 -163,6 +163,8 @@@ article h3 { margin: 40px 0 16px; 
  // Miscellaneous.
  //----------------------------------------
  
 +.figures h2 { margin-top: 100px; }
 +
  .maintitle {
    text-align: center;
  }