Looks like markdown doesn't support links in ASCII-art blocks.

sky/sdk/lib/README.md

Index: sky/sdk/lib/README.md
diff --git a/sky/sdk/lib/README.md b/sky/sdk/lib/README.md
index 4b58e3c3ea2a61f529f58309270721c78990fd63..3bfbfbf49fafadb24c6d1b777e22e145b552fe36 100644
--- a/sky/sdk/lib/README.md
+++ b/sky/sdk/lib/README.md
@@ -5,7 +5,8 @@ Sky and Sky's SDK are designed as layered frameworks, where each layer
 depends on the ones below it but could be replaced wholesale.
 
 The bottom-most layer is the Sky Platform, which is exposed to Dart
-code as various ```dart:``` packages, including ```dart:sky```.
+code as [various ```dart:``` packages](https://api.dartlang.org/),
+including ```dart:sky```.
 
 The [base/](base/) directory contains libraries that extend these core
 APIs to provide base classes for tree structures
@@ -39,28 +40,26 @@ implemented in the host system's preferred language.
 
 Here is a diagram summarising all this:
 
-```
-  +-----------------------------+ ------
-  |           YOUR APP          |
-  |     +--------------------+--+ 
-  |     |      [editing/](editing/)      |  |
-  |  +--+-------------------++  |
-  |  |  [widgets/](widgets/)  ([theme/](theme/))  |   |
-  | ++---------------------++   |  Dart
-  | |      [rendering/](rendering/)      |    |
-  +-+---------+------------+    |
-  | [painting/](painting/) | [animation/](animation/) |    |
-  +---------------+--------+    |
-  |    [base/](base/)      |  [mojo/](mojo/)      |
-  +------------+--+-+----+------+ -------
-  |  dart:sky  |    |    | Host |
-  +--------+---+    |    | APIs |  C++
-  |  Skia  |  [Dart](https://api.dartlang.org/)  |    +------+  ObjC
-  +--------+--------+           |  Java
-  |            Mojo             |
-  +-----------------------------+ -------
-  |    Host Operating System    |  C/C++
-  +-----------------------------+ -------
-```
+    +-----------------------------+ ------
+    |           YOUR APP          |
+    |     +--------------------+--+ 
+    |     |      editing/      |  |
+    |  +--+-------------------++  |
+    |  |  widgets/  (theme/)  |   |
+    | ++---------------------++   |  Dart
+    | |      rendering/      |    |
+    +-+---------+------------+    |
+    | painting/ | animation/ |    |
+    +---------------+--------+    |
+    |    base/      |  mojo/      |
+    +------------+--+-+----+------+ -------
+    |  dart:sky  |    |    | Host |
+    +--------+---+    |    | APIs |  C++
+    |  Skia  |  Dart  |    +------+  ObjC
+    +--------+--------+           |  Java
+    |            Mojo             |
+    +-----------------------------+ -------
+    |    Host Operating System    |  C/C++
+    +-----------------------------+ -------
 
 TODO(ianh): document dart:sky and the Host APIs somewhere