Merge pull request python3statement#25 from Carreau/legend

Add legend for timeline.

Author: takluyver

_sections/40-timeline.md

@@ -15,4 +15,8 @@ extended support. (Python's own timeline is available
 
 <div id="visualization"></div>
 
+<div>
+    <p class=" py2">Compatible with Python 2 and Python 3.</p>
+    <p class="py3">Compatible with Python 3 only.</p>
+</div>
 See how to [add  your project to the list of participating projects](https://github.com/python3statement/python3statement.github.io#add-your-project) and to [this timeline](https://github.com/python3statement/python3statement.github.io#add-timeline-information)

combo.css

@@ -4,15 +4,23 @@
 {% include css/skeleton.css %}
 {% include css/main.css %}
 
-div.vis-item {
+div.vis-item , p.py3{
      background-color:#03acf6;
      color: white;
 }
 
 
-div.vis-item.py2 {
+div.vis-item.py2, p.py2 {
       background-color: #3dbf18;
       border-color: #3dbf18;
+      color:white; 
+
+}
+
+p.py2:first-child, p.py3:first-child{
+    margin-top: 0px;
+    margin-bottom: 5px;
+
 }
 
 div.vis-item.vis-selected {