Update CSS to fix homepage issues

Change-Id: I8f6e980a990f76c5d791271d2ad52fe5ced27905

Documentation/markdown.md

diff --git a/Documentation/markdown.md b/Documentation/markdown.md
index 05fe794..23020ff 100644
--- a/Documentation/markdown.md
+++ b/Documentation/markdown.md
@@ -163,20 +163,20 @@
 Cells may span multiple columns and include formatting accepted within
 paragraphs such as emphasis, images or links:
 
-|              | Grouping                    ||  
-| First Header | Second Header | Third Header |  
-| ------------ | :-----------: | -----------: |  
-| Content      | *Long Cell*                 ||  
-| Content      | **Cell 2**    | Cell 3       |  
+|              | Grouping                    ||
+| First Header | Second Header | Third Header |
+| ------------ | :-----------: | -----------: |
+| Content      | *Long Cell*                 ||
+| Content      | **Cell 2**    | Cell 3       |
 
 the above table was created by:
 
 ```
-|              | Grouping                    ||  
-| First Header | Second Header | Third Header |  
-| ------------ | :-----------: | -----------: |  
-| Content      | *Long Cell*                 ||  
-| Content      | **Cell 2**    | Cell 3       |  
+|              | Grouping                    ||
+| First Header | Second Header | Third Header |
+| ------------ | :-----------: | -----------: |
+| Content      | *Long Cell*                 ||
+| Content      | **Cell 2**    | Cell 3       |
 ```
 
 Empty table cells are indicated by whitespace between the column
@@ -258,7 +258,7 @@
 
  ```c
  #include <stdio.h>
- 
+
  int main() {
    printf("Hello, World.\n");
    return 0;
@@ -285,7 +285,7 @@
 * ruby
 * tcl
 
-### Web
+#### Web
 * css
 * dart
 * html

gitiles-servlet/src/main/resources/com/google/gitiles/static/doc.css

diff --git a/gitiles-servlet/src/main/resources/com/google/gitiles/static/doc.css b/gitiles-servlet/src/main/resources/com/google/gitiles/static/doc.css
index ca35407..d10b403 100644
--- a/gitiles-servlet/src/main/resources/com/google/gitiles/static/doc.css
+++ b/gitiles-servlet/src/main/resources/com/google/gitiles/static/doc.css
@@ -49,6 +49,12 @@
   font-size: 14px;
   font-style: italic;
 }
+.doc hr {
+  border: none;
+  border-top: 1px solid #aaa;
+  display: block;
+  margin-top: 25px;
+}
 .doc a {
   text-decoration: none;
 }
@@ -230,12 +236,19 @@
 .aside p:last-child {
   margin-bottom: 0;
 }
+.cols {
+  margin: 0 -1.533%;
+  width: 103.067%;
+}
 .col-1, .col-2, .col-3, .col-4, .col-5, .col-6,
 .col-7, .col-8, .col-9, .col-10, .col-11, .col-12 {
   display: inline-block;
-  margin-bottom: 20px;
+  margin: 0 1.488% 20px;
   vertical-align: top;
 }
+.cols h1, .cols h2, .cols h3, .cols h4, .cols h5, .cols h6 {
+  margin: .67em 0;
+}
 .col-1 { width: 5.357%; }
 .col-2 { width: 13.690%; }
 .col-3 { width: 22.024%; }