Update stylesheets to format NaCl demos.

Review URL: https://codereview.chromium.org/875593002

Cr-Commit-Position: refs/heads/master@{#313340}

chrome/common/extensions/docs/static/sass/_demos.scss

+.demo {
+  * {
+    box-sizing: border-box;
+    webkit-box-sizing: border-box;
+  }
+
+  div {
+    flex: 1 1 auto;
+
+    .panel-info {
+      border-top: 1px solid #cccccc;
+      margin-top: 20px;
+      padding-top: 20px;
+    }
+  }
+
+  div.Demo-body {
+    border: 1px solid #dfdfdf;
+    display: flex;
+    flex-direction: column;
+    padding: 10px;
+    position: relative;
+
+    embed {
+      display: block;
+      flex: 1 1 auto;
+    }
+  }
+
+  div.Demo-content {
+    display: flex;
+    flex-direction: column;
+  }
+
+  div.intro {
+    display: flex;
+    flex-direction: column;
+  }
+  
+  header {
+    padding: 0;
+  }
+
+  .intro {
+    max-width: 360px;
+    padding-right: 40px;
+  }
+
+  p {
+    margin: 0 0 1em 0;
+  }
+
+  p.note {
+    background: transparent;
+    border: none;
+    padding: 0;
+    width: 100%;
+  }
+
+  section {
+    display: flex;
+    flex: 1 1 auto;
+    flex-direction: row;
+    padding: 0 25px 25px 0;
+  }
+
+  td, th {
+    border: none;
+  }
+
+  td.name, th.name {
+    font-weight: bold;
+  }
+
+  tr {
+    border: none;
+  }
+}

chrome/common/extensions/docs/static/sass/site.scss

@@ -26,3 +26,4 @@
 @import "pillar";
 @import "article";
 @import "api";
+@import "demos";