Respect label size

Gemfile.lock

@@ -17,7 +17,7 @@ GEM
     css_parser (1.4.9)
       addressable
     excon (0.55.0)
-    json (1.8.3)
+    json (1.8.6)
     pdf-core (0.6.1)
     prawn (2.1.0)
       pdf-core (~> 0.6.1)

main.rb

@@ -70,8 +70,9 @@ end
 def render_label(label)
 
   label = api("labels/#{label}")
+  length, width = label["style"].values_at("length", "width")
 
-  pdf = Prawn::Document.new(page_size: [89, 36].map { |x| mm2pt(x) },
+  pdf = Prawn::Document.new(page_size: [length, width].map { |x| mm2pt(x) },
                             margin: [2, 2, 2, 6].map { |x| mm2pt(x) }) do
     font_families.update("DejaVuSans" => {
       normal: "fonts/DejaVuSans.ttf",