website: mobile css tweaks

- make it so on small screens (mobile), code blocks don't
  run off the screen
- make the gutters a bit smaller on mobile, to not waste too
  much real estate

Change-Id: Ifd07a47b8ac0e37e6aab0424b3fa43030afc1500
diff --git a/stylesheets/code.less b/stylesheets/code.less
index d76f54b..eaea532 100644
--- a/stylesheets/code.less
+++ b/stylesheets/code.less
@@ -18,6 +18,10 @@
   margin: 0 -@gutter-half;
   width: @pre-width;
 
+  @media @small-screen {
+    width: auto;
+  }
+
   /* Include <pre> because clipboard buttons are in <pre>, not <code>. */
   &, & code, & .hljs {
     &:not(.noclipboard) {
diff --git a/stylesheets/index.less b/stylesheets/index.less
index 8062340..8992980 100644
--- a/stylesheets/index.less
+++ b/stylesheets/index.less
@@ -157,6 +157,10 @@
   padding: 0 calc(@gutter + @gutter-half) @gutter;
   max-width: @main-max-width;
 
+  @media @small-screen {
+    padding: 0 @gutter @gutter;
+  }
+
   /* Prevent headings from being obscured by the <header> for #heading urls. */
   h1[id], h2[id], h3[id], h4[id], h5[id], h6[id] {
     /**