gistfile1.rb

# We start with no Content-Type, and in Response#finish it is set to text/html
get "/one" do
  erb :example
end

# Start with no Content-Type, sass() sets Content-Type to text/css, Response#finish doesn't touch it,
# because it already has been set, and thus what should have been text/html is now text/css
get "/two" do
  erb :sass_example
end

# .. therefore, to have the pure-CSS work and sass() setting Content-Type = 'text/css' you would have
# to explicitly set the content type to text/html when using sass()-helper in view
get "/three" do
  erb :sass_example
  content_type 'text/html'
end

__END__
@@ example
<p>Some text</p>

@@ sass_example
<p>Here's some example CSS:</p>
<pre><code><%= sass(:foo) %></code></pre>