diff --git a/README.md b/README.md
index c223146d..02a46ace 100644
--- a/README.md
+++ b/README.md
@@ -130,6 +130,31 @@ kramdown:
       directory: path/to/themes
 ```
 
+### Dimensions and Styling
+
+It's possible to customize the dimensions of the diagram by providing the
+`width` and `height` configuration keys. It's also possible to add arbitrary
+styling with the `style` key.
+
+```yaml
+kramdown:
+  plantuml:
+    width: 200px
+    height: 100px
+    style: "border: 1px solid black"
+```
+
+To remove the `width`, `height` and `style` attributes from the `<svg />`
+element, set the key's value to `none`.
+
+```yaml
+kramdown:
+  plantuml:
+    width: none
+    height: none
+    style: none
+```
+
 ### Errors
 
 By default, `kramdown-plantuml` will raise an error and crash if something goes
@@ -199,7 +224,7 @@ agreement][cla].
 [codacy]:               https://www.codacy.com/gh/SwedbankPay/kramdown-plantuml/dashboard?utm_source=github.com&amp;utm_medium=referral&amp;utm_content=SwedbankPay/kramdown-plantuml&amp;utm_campaign=Badge_Grade
 [codecov-badge]:        https://codecov.io/gh/SwedbankPay/kramdown-plantuml/branch/main/graph/badge.svg?token=U3QJLVG3HY
 [codecov]:              https://codecov.io/gh/SwedbankPay/kramdown-plantuml/
-[diagram-svg]:          ./spec/examples/diagram.svg
+[diagram-svg]:          ./spec/examples/network-diagram.svg
 [fenced]:               https://www.markdownguide.org/extended-syntax/#syntax-highlighting
 [fork]:                 https://docs.github.com/en/free-pro-team@latest/github/getting-started-with-github/fork-a-repo
 [gem-badge]:            https://badge.fury.io/rb/kramdown-plantuml.svg
diff --git a/kramdown-plantuml.gemspec b/kramdown-plantuml.gemspec
index 7260872c..c86819da 100644
--- a/kramdown-plantuml.gemspec
+++ b/kramdown-plantuml.gemspec
@@ -42,6 +42,7 @@ Gem::Specification.new do |spec|
 
   spec.add_development_dependency 'rake', '~> 13.0'
   spec.add_development_dependency 'rspec', '~> 3.2'
+  spec.add_development_dependency 'rspec-html-matchers', '>= 0.9'
   spec.add_development_dependency 'rspec-its', '~> 1.3'
   spec.add_development_dependency 'rubocop', '~> 1.12'
   spec.add_development_dependency 'rubocop-rake', '~> 0.6'
diff --git a/lib/kramdown-plantuml/executor.rb b/lib/kramdown-plantuml/executor.rb
index 59e3bb36..575c4e76 100644
--- a/lib/kramdown-plantuml/executor.rb
+++ b/lib/kramdown-plantuml/executor.rb
@@ -26,7 +26,7 @@ def initialize
 
       def execute(diagram)
         raise ArgumentError, 'diagram cannot be nil' if diagram.nil?
-        raise ArgumentError, "diagram must be a #{Diagram}" unless diagram.is_a?(Diagram)
+        raise ArgumentError, "diagram must be a #{PlantUmlDiagram}" unless diagram.is_a?(PlantUmlDiagram)
 
         cmd = "java -Djava.awt.headless=true -jar #{@plantuml_jar_file} -tsvg -failfast -pipe #{debug_args}"
 
diff --git a/lib/kramdown-plantuml/jekyll_page_processor.rb b/lib/kramdown-plantuml/jekyll_page_processor.rb
index 23a3d092..14aa0e13 100644
--- a/lib/kramdown-plantuml/jekyll_page_processor.rb
+++ b/lib/kramdown-plantuml/jekyll_page_processor.rb
@@ -91,8 +91,8 @@ def replace_needle(json)
       def decode_and_convert(hash, options)
         encoded_plantuml = hash['plantuml']
         plantuml = HTMLEntities.new.decode encoded_plantuml
-        diagram = ::Kramdown::PlantUml::Diagram.new(plantuml, options)
-        diagram.convert_to_svg
+        diagram = ::Kramdown::PlantUml::PlantUmlDiagram.new(plantuml, options)
+        diagram.svg
       end
 
       def logger
diff --git a/lib/kramdown-plantuml/none_s.rb b/lib/kramdown-plantuml/none_s.rb
new file mode 100644
index 00000000..7ff444ef
--- /dev/null
+++ b/lib/kramdown-plantuml/none_s.rb
@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+# Ruby's Object class.
+class Object
+  # Performs a case insensitive, trimmed comparison of the Object and the
+  # String 'none' and Symbol :none. Returns true if the comparison is true,
+  # otherwise false.
+  #
+  # @return [Boolean] True if the Object is equal to 'none' or :none,
+  # otherwise false.
+  def none_s?
+    return false if nil?
+    return true if self == :none
+
+    to_s.strip.casecmp?('none')
+  end
+end
diff --git a/lib/kramdown-plantuml/options.rb b/lib/kramdown-plantuml/options.rb
index bd9ae51c..7210b373 100644
--- a/lib/kramdown-plantuml/options.rb
+++ b/lib/kramdown-plantuml/options.rb
@@ -1,18 +1,20 @@
 # frozen_string_literal: true
 
+require_relative 'none_s'
 require_relative 'log_wrapper'
 
 module Kramdown
   module PlantUml
     # Options for PlantUML processing
     class Options
-      attr_reader :theme_name, :theme_directory
+      attr_reader :theme_name, :theme_directory, :width, :height, :style
 
       def initialize(options_hash = {})
         @logger = LogWrapper.init
         @options = massage(options_hash) || {}
         @raise_errors = extract_raise_errors(@options)
         extract_theme_options(@options)
+        extract_style_options(@options)
       end
 
       def raise_errors?
@@ -64,6 +66,23 @@ def extract_raise_errors(options)
         boolean(raise_errors, true)
       end
 
+      def extract_style_options(options)
+        return if options.nil? || options.empty?
+
+        set_instance_property(:width, options)
+        set_instance_property(:height, options)
+        set_instance_property(:style, options)
+      end
+
+      def set_instance_property(name, options)
+        return unless options.key? name
+
+        value = options[name]
+        value = :none if value.none_s?
+        prop_name = "@#{name}".to_sym
+        instance_variable_set(prop_name, value)
+      end
+
       def massage(options_hash)
         if options_hash.nil? || !options_hash.is_a?(Hash) || options_hash.empty?
           @logger.debug 'No options provided'
diff --git a/lib/kramdown-plantuml/diagram.rb b/lib/kramdown-plantuml/plantuml_diagram.rb
similarity index 66%
rename from lib/kramdown-plantuml/diagram.rb
rename to lib/kramdown-plantuml/plantuml_diagram.rb
index 8a9b29f2..cd70851b 100644
--- a/lib/kramdown-plantuml/diagram.rb
+++ b/lib/kramdown-plantuml/plantuml_diagram.rb
@@ -1,17 +1,18 @@
 # frozen_string_literal: true
 
-require_relative 'version'
-require_relative 'theme'
+require_relative 'executor'
+require_relative 'log_wrapper'
 require_relative 'options'
 require_relative 'plantuml_error'
-require_relative 'log_wrapper'
-require_relative 'executor'
+require_relative 'svg_diagram'
+require_relative 'theme'
+require_relative 'version'
 
 module Kramdown
   module PlantUml
     # Represents a PlantUML diagram that can be converted to SVG.
-    class Diagram
-      attr_reader :theme, :plantuml, :result
+    class PlantUmlDiagram
+      attr_reader :theme, :plantuml, :result, :options
 
       def initialize(plantuml, options)
         raise ArgumentError, 'options cannot be nil' if options.nil?
@@ -25,15 +26,13 @@ def initialize(plantuml, options)
         @logger.warn 'PlantUML diagram is empty' if @plantuml.nil? || @plantuml.empty?
       end
 
-      def convert_to_svg
-        return @svg unless @svg.nil?
-        return @plantuml if @plantuml.nil? || @plantuml.empty?
+      def svg
+        return @svg_diagram unless @svg_diagram.nil?
 
         @plantuml = @theme.apply(@plantuml)
         log(plantuml)
         @result = @executor.execute(self)
-        @result.validate
-        @svg = wrap(@result.without_xml_prologue)
+        @svg_diagram = SvgDiagram.new(@result)
       rescue StandardError => e
         raise e if @options.raise_errors?
 
@@ -42,16 +41,6 @@ def convert_to_svg
 
       private
 
-      def wrap(svg)
-        theme_class = @theme.name ? "theme-#{@theme.name}" : ''
-        class_name = "plantuml #{theme_class}".strip
-
-        wrapper_element_start = "<div class=\"#{class_name}\">"
-        wrapper_element_end = '</div>'
-
-        "#{wrapper_element_start}#{svg}#{wrapper_element_end}"
-      end
-
       def log(plantuml)
         @logger.debug 'PlantUML converting diagram:'
         @logger.debug_multiline plantuml
diff --git a/lib/kramdown-plantuml/plantuml_error.rb b/lib/kramdown-plantuml/plantuml_error.rb
index 1cc8adeb..cc24beb9 100644
--- a/lib/kramdown-plantuml/plantuml_error.rb
+++ b/lib/kramdown-plantuml/plantuml_error.rb
@@ -31,11 +31,11 @@ def create_message(result)
       end
 
       def header(result)
-        if theme_not_found?(result) && !result.diagram.nil? && !result.diagram.theme.nil?
+        if theme_not_found?(result) && !result.plantuml_diagram.nil? && !result.plantuml_diagram.theme.nil?
           return <<~HEADER
             Conversion of the following PlantUML result failed because the
-            theme '#{result.diagram.theme.name}' can't be found in the directory
-            '#{result.diagram.theme.directory}':
+            theme '#{result.plantuml_diagram.theme.name}' can't be found in the directory
+            '#{result.plantuml_diagram.theme.directory}':
           HEADER
         end
 
@@ -50,9 +50,9 @@ def theme_not_found?(result)
       end
 
       def plantuml(result)
-        return nil if result.nil? || result.diagram.nil?
+        return nil if result.nil? || result.plantuml_diagram.nil?
 
-        result.diagram.plantuml
+        result.plantuml_diagram.plantuml
       end
 
       def result(result)
diff --git a/lib/kramdown-plantuml/plantuml_result.rb b/lib/kramdown-plantuml/plantuml_result.rb
index 5108b930..779b2eed 100644
--- a/lib/kramdown-plantuml/plantuml_result.rb
+++ b/lib/kramdown-plantuml/plantuml_result.rb
@@ -2,46 +2,29 @@
 
 require_relative 'log_wrapper'
 require_relative 'plantuml_error'
-require_relative 'diagram'
+require_relative 'svg_diagram'
 
 module Kramdown
   module PlantUml
     # Executes the PlantUML Java application.
     class PlantUmlResult
-      attr_reader :diagram, :stdout, :stderr, :exitcode
+      attr_reader :plantuml_diagram, :stdout, :stderr, :exitcode
 
-      def initialize(diagram, stdout, stderr, exitcode)
-        raise ArgumentError, 'diagram cannot be nil' if diagram.nil?
-        raise ArgumentError, "diagram must be a #{Diagram}" unless diagram.is_a?(Diagram)
+      def initialize(plantuml_diagram, stdout, stderr, exitcode)
+        raise ArgumentError, 'diagram cannot be nil' if plantuml_diagram.nil?
+        raise ArgumentError, "diagram must be a #{PlantUmlDiagram}" unless plantuml_diagram.is_a?(PlantUmlDiagram)
         raise ArgumentError, 'exitcode cannot be nil' if exitcode.nil?
         raise ArgumentError, "exitcode must be a #{Integer}" unless exitcode.is_a?(Integer)
 
-        @diagram = diagram
+        @plantuml_diagram = plantuml_diagram
         @stdout = stdout
         @stderr = stderr
         @exitcode = exitcode
         @logger = LogWrapper.init
       end
 
-      def without_xml_prologue
-        return @stdout if @stdout.nil? || @stdout.empty?
-
-        xml_prologue_start = '<?xml'
-        xml_prologue_end = '?>'
-
-        start_index = @stdout.index(xml_prologue_start)
-
-        return @stdout if start_index.nil?
-
-        end_index = @stdout.index(xml_prologue_end, xml_prologue_start.length)
-
-        return @stdout if end_index.nil?
-
-        end_index += xml_prologue_end.length
-
-        @stdout.slice! start_index, end_index
-
-        @stdout
+      def svg_diagram
+        @plantuml_diagram.svg
       end
 
       def valid?
@@ -53,7 +36,7 @@ def valid?
         @stderr.include?('CoreText note:')
       end
 
-      def validate
+      def validate!
         raise PlantUmlError, self unless valid?
 
         return if @stderr.nil? || @stderr.empty?
diff --git a/lib/kramdown-plantuml/style_builder.rb b/lib/kramdown-plantuml/style_builder.rb
new file mode 100644
index 00000000..4b798aaa
--- /dev/null
+++ b/lib/kramdown-plantuml/style_builder.rb
@@ -0,0 +1,56 @@
+# frozen_string_literal: true
+
+require_relative 'none_s'
+
+module Kramdown
+  module PlantUml
+    # Builds a CSS style string from a hash of style properties.
+    class StyleBuilder
+      def initialize
+        @hash = {}
+      end
+
+      def []=(key, value)
+        return if key.nil?
+
+        case key
+        when :width, :height
+          if none(value)
+            @hash.delete(key)
+          else
+            @hash[key] = value
+          end
+        else
+          self.style = value
+        end
+      end
+
+      def to_s
+        @hash.sort_by { |key, _| key }.map { |key, value| "#{key}:#{value}" }.join(';')
+      end
+
+      private
+
+      def none(value)
+        return true if value.nil?
+
+        value_s = value.to_s.strip
+
+        return true if value_s.empty? || value.none_s?
+
+        false
+      end
+
+      def style=(style)
+        return if style.nil? || style.strip.empty?
+
+        style.split(';').each do |pair|
+          key, value = pair.split(':')
+          key = key.strip.to_sym
+          value = value.strip
+          @hash[key] = value
+        end
+      end
+    end
+  end
+end
diff --git a/lib/kramdown-plantuml/svg_diagram.rb b/lib/kramdown-plantuml/svg_diagram.rb
new file mode 100644
index 00000000..a50be932
--- /dev/null
+++ b/lib/kramdown-plantuml/svg_diagram.rb
@@ -0,0 +1,115 @@
+# frozen_string_literal: true
+
+require 'rexml/document'
+require_relative 'none_s'
+require_relative 'style_builder'
+require_relative 'plantuml_diagram'
+
+module Kramdown
+  module PlantUml
+    # A diagram in SVG format.
+    class SvgDiagram
+      def initialize(plantuml_result)
+        raise ArgumentError, 'plantuml_result cannot be nil' if plantuml_result.nil?
+        raise ArgumentError, "plantuml_result must be a #{PlantUmlResult}" unless plantuml_result.is_a?(PlantUmlResult)
+
+        plantuml_result.validate!
+        svg = plantuml_result.stdout
+        @doc = REXML::Document.new svg
+        @source = plantuml_result.plantuml_diagram
+        @style_builder = StyleBuilder.new
+        transfer_options(plantuml_result)
+      end
+
+      def to_s
+        return '' if @doc.root.nil?
+
+        wrapper_doc = REXML::Document.new
+        wrapper_doc.context[:attribute_quote] = :quote
+        wrapper_element = REXML::Element.new('div').tap do |div|
+          div.add_attribute 'class', wrapper_class_name
+          div.add_element @doc.root
+        end
+
+        wrapper_doc.add_element wrapper_element
+        wrapper_doc.to_s
+      end
+
+      def width
+        get_xml_attribute_value(:width)
+      end
+
+      def height
+        get_xml_attribute_value(:height)
+      end
+
+      def style
+        get_xml_attribute_value(:style)
+      end
+
+      private
+
+      def wrapper_class_name
+        theme_class = @source.theme.name ? "theme-#{@source.theme.name}" : ''
+        "plantuml #{theme_class}".strip
+      end
+
+      def get_xml_attribute_value(attribute_name)
+        return nil if @doc.root.nil?
+
+        name = attribute_name.to_s
+        value = @doc.root.attributes[name]
+        value.nil? || value.none_s? ? :none : value
+      end
+
+      def manipulate_xml_attribute(attribute_name, value)
+        if value.none_s?
+          remove_xml_attribute(attribute_name)
+        elsif !value.nil? && value.is_a?(String) && !value.strip.empty?
+          set_xml_attribute(attribute_name, value)
+        end
+
+        update_style unless attribute_name == :style || style == :none
+      end
+
+      def remove_xml_attribute(attribute_name)
+        @doc.root.attributes.get_attribute(attribute_name.to_s).remove
+      end
+
+      def set_xml_attribute(attribute_name, value)
+        name = attribute_name.to_s
+        @doc.root.attributes[name] = value
+        @style_builder[attribute_name] = value
+      end
+
+      def update_style
+        style = @style_builder.to_s
+        set_xml_attribute(:style, style)
+      end
+
+      def transfer_options(plantuml_result)
+        return if (options = options(plantuml_result)).nil?
+
+        %i[style width height].each do |attribute|
+          options.public_send(attribute).tap do |option_value|
+            next if option_value.nil?
+
+            option_value = option_value.to_s.strip
+
+            next if option_value.empty?
+
+            manipulate_xml_attribute(attribute, option_value)
+          end
+        end
+      end
+
+      def options(plantuml_result)
+        return nil if @doc.root.nil? \
+          || plantuml_result.nil? \
+          || plantuml_result.plantuml_diagram.nil?
+
+        plantuml_result.plantuml_diagram.options
+      end
+    end
+  end
+end
diff --git a/lib/kramdown_html.rb b/lib/kramdown_html.rb
index a7a40768..09c8d1ae 100644
--- a/lib/kramdown_html.rb
+++ b/lib/kramdown_html.rb
@@ -5,7 +5,7 @@
 require_relative 'kramdown-plantuml/log_wrapper'
 require_relative 'kramdown-plantuml/plantuml_error'
 require_relative 'kramdown-plantuml/options'
-require_relative 'kramdown-plantuml/diagram'
+require_relative 'kramdown-plantuml/plantuml_diagram'
 require_relative 'kramdown-plantuml/jekyll_provider'
 
 module Kramdown
@@ -38,8 +38,8 @@ def plantuml?(element)
       end
 
       def convert_plantuml(plantuml, options)
-        diagram = ::Kramdown::PlantUml::Diagram.new(plantuml, options)
-        diagram.convert_to_svg
+        diagram = ::Kramdown::PlantUml::PlantUmlDiagram.new(plantuml, options)
+        diagram.svg.to_s
       rescue StandardError => e
         raise e if options.raise_errors?
 
diff --git a/spec/examples/_config.yml b/spec/examples/_config.yml
index 9cba6e78..692aa187 100644
--- a/spec/examples/_config.yml
+++ b/spec/examples/_config.yml
@@ -1,2 +1 @@
-plugins:
-  - kramdown-plantuml
+plugins: [kramdown-plantuml]
diff --git a/spec/examples/_layouts/default.html b/spec/examples/_layouts/default.html
new file mode 100644
index 00000000..679ff825
--- /dev/null
+++ b/spec/examples/_layouts/default.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html lang="en-US">
+    <head>
+        <meta charset="utf-8" />
+        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+        <title>kramdown::plantuml</title>
+    </head>
+    <body>
+        {{ content }}
+    </body>
+</html>
diff --git a/spec/examples/index.md b/spec/examples/index.md
index 019fe2f2..ff36d5eb 100644
--- a/spec/examples/index.md
+++ b/spec/examples/index.md
@@ -1,9 +1,12 @@
 ---
 title: Fixture
+layout: default
 ---
 
 # This is a fixture
 
+## Network diagram
+
 ```plantuml
 @startuml Diagram
 actor client
@@ -13,3 +16,129 @@ db -> app
 app -> client
 @enduml
 ```
+
+## Sequence diagram
+
+```plantuml
+@startuml "Sequence"
+    title "Checkout Sequence"
+
+    group Checkin
+        Payer --> Merchant: Start Checkin
+        activate Payer
+            activate Merchant
+                Merchant --> SwedbankPay: POST /psp/consumers
+                activate SwedbankPay
+                    SwedbankPay --> Merchant: rel:view-consumer-identification ①
+                deactivate SwedbankPay
+                Merchant --> Payer: Show Checkin on Merchant Page
+            deactivate Merchant
+
+            SwedbankPay <-> Payer: Consumer identification process
+        deactivate Payer
+
+        activate SwedbankPay
+            SwedbankPay ->> Merchant: onConsumerIdentified(consumerProfileRef) ④
+        deactivate SwedbankPay
+        activate Merchant
+        deactivate Merchant
+    end group
+
+    group#fff #ebf8f2 Payment Menu
+        Payer -> Merchant: Initiate Purchase
+        deactivate Payer
+        Merchant -> SwedbankPay: POST /psp/paymentorders { paymentUrl, consumerProfileRef }
+        deactivate Merchant
+        SwedbankPay --> Merchant: rel:view-paymentorder
+        deactivate SwedbankPay
+        Merchant --> Payer: Display Payment Menu on Merchant Page
+        activate Payer
+        Payer ->> Payer: Initiate Payment Menu Hosted View (open iframe)
+        Payer --> SwedbankPay: Show Payment UI page in iframe
+        deactivate Payer
+        SwedbankPay -> Payer: Do payment logic
+        deactivate SwedbankPay
+        Payer ->> SwedbankPay: Do payment logic
+        deactivate Payer
+
+        opt Consumer perform payment out of iFrame
+            Payer ->> Payer: Redirect to 3rd party
+            Payer -> 3rdParty: Redirect to 3rdPartyUrl URL
+            deactivate Payer
+            3rdParty --> Payer: Redirect back to paymentUrl (merchant)
+            deactivate 3rdParty
+            Payer ->> Payer: Initiate Payment Menu Hosted View (open iframe)
+            Payer -> SwedbankPay: Show Payment UI page in iframe
+            deactivate Payer
+        end
+
+        SwedbankPay -->> Payer: Payment status
+
+        alt If payment is completed
+            activate Payer
+            Payer ->> Payer: Event: onPaymentCompleted
+            Payer -> Merchant: Check payment status
+            deactivate Payer
+            Merchant -> SwedbankPay: GET <paymentorder.id>
+            deactivate Merchant
+            SwedbankPay -> Merchant: rel: paid-paymentorder
+            deactivate SwedbankPay
+            opt#fff #eee Get PaymentOrder Details (if paid-paymentorder operation exist)
+                activate Merchant
+                    Merchant -> SwedbankPay: GET rel:paid-paymentorder.href
+                    activate SwedbankPay
+                        SwedbankPay -->> Merchant: Payment Details
+                    deactivate SwedbankPay
+                deactivate Merchant
+            end
+        end
+    end group
+
+    opt If payment is failed
+        activate Payer
+        Payer ->> Payer: Event: OnPaymentFailed
+        Payer -> Merchant: Check payment status
+        deactivate Payer
+        Merchant -> SwedbankPay: GET {paymentorder.id}
+        deactivate Merchant
+        SwedbankPay --> Merchant: rel: failed-paymentorder
+
+        deactivate SwedbankPay
+        opt Get PaymentOrder Details (if failed-paymentorder operation exist)
+            activate Payer
+            deactivate Payer
+            Merchant -> SwedbankPay: GET rel: failed-paymentorder
+            deactivate Merchant
+            SwedbankPay -->> Merchant: Payment Details
+            deactivate SwedbankPay
+        end
+    end
+
+    activate Merchant
+    Merchant --> Payer: Show Purchase complete
+    opt PaymentOrder Callback (if callbackUrls is set)
+        activate Payer
+        deactivate Payer
+            SwedbankPay ->> Merchant: POST Payment Callback
+    end
+
+    group Capture
+        note left of Merchant
+            Capture here only if the purchased goods don't require shipping.
+            If shipping is required, perform capture after the goods have
+            shipped. Should only be used for PaymentInstruments that support
+            Authorizations.
+        end note
+
+        Merchant -> Merchant: Capture
+        activate Merchant
+            Merchant -> SwedbankPay: GET {paymentorder.id}
+            activate SwedbankPay
+                SwedbankPay --> Merchant: paymentorder
+                Merchant -> SwedbankPay: rel:create-paymentorder-capture
+                SwedbankPay --> Merchant: Capture status
+            deactivate SwedbankPay
+        deactivate Merchant
+    end group
+@enduml
+```
diff --git a/spec/examples/diagram.plantuml b/spec/examples/network-diagram.puml
similarity index 100%
rename from spec/examples/diagram.plantuml
rename to spec/examples/network-diagram.puml
diff --git a/spec/examples/diagram.svg b/spec/examples/network-diagram.svg
similarity index 100%
rename from spec/examples/diagram.svg
rename to spec/examples/network-diagram.svg
diff --git a/spec/executor_spec.rb b/spec/executor_spec.rb
index 3db3a2d8..0b892743 100644
--- a/spec/executor_spec.rb
+++ b/spec/executor_spec.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: false
 
 require 'rspec/its'
-require 'kramdown-plantuml/diagram'
+require 'kramdown-plantuml/plantuml_diagram'
 
 Executor = ::Kramdown::PlantUml::Executor
 
@@ -29,8 +29,8 @@
       it { expect { subject.execute(nil) }.to raise_error(ArgumentError, 'diagram cannot be nil') }
     end
 
-    context 'diagram is not Diagram' do
-      it { expect { subject.execute('') }.to raise_error(ArgumentError, "diagram must be a #{Diagram}") }
+    context 'diagram is not PlantUmlDiagram' do
+      it { expect { subject.execute('') }.to raise_error(ArgumentError, "diagram must be a #{Kramdown::PlantUml::PlantUmlDiagram}") }
     end
   end
 end
diff --git a/spec/jekyll_page_processor_spec.rb b/spec/jekyll_page_processor_spec.rb
index a4746179..97d6db98 100644
--- a/spec/jekyll_page_processor_spec.rb
+++ b/spec/jekyll_page_processor_spec.rb
@@ -4,7 +4,7 @@
 require 'kramdown-plantuml/options'
 require 'kramdown-plantuml/jekyll_page_processor'
 
-Options = Kramdown::PlantUml::Options
+Options ||= Kramdown::PlantUml::Options
 JekyllPageProcessor = ::Kramdown::PlantUml::JekyllPageProcessor
 
 describe JekyllPageProcessor do
diff --git a/spec/jekyll_provider_spec.rb b/spec/jekyll_provider_spec.rb
index e1739875..8af389ae 100644
--- a/spec/jekyll_provider_spec.rb
+++ b/spec/jekyll_provider_spec.rb
@@ -4,11 +4,11 @@
 require 'kramdown-plantuml/options'
 require 'kramdown-plantuml/jekyll_provider'
 
-Options = Kramdown::PlantUml::Options
+Options ||= Kramdown::PlantUml::Options
 JekyllProvider = ::Kramdown::PlantUml::JekyllProvider
 
 describe JekyllProvider do
-  let (:plantuml_file_contents) { File.read(File.join(__dir__, 'examples', 'diagram.plantuml')) }
+  let (:plantuml_file_contents) { File.read(File.join(__dir__, 'examples', 'network-diagram.puml')) }
   let (:plantuml) { nil }
   let (:options) { Options.new }
   subject { JekyllProvider }
@@ -59,8 +59,13 @@
       subject { File.read(File.join(jekyll_destination, 'index.html')) }
 
       context 'when plantuml contains HTML entities', :jekyll do
-        it { is_expected.to match(/<div class="plantuml"><svg.*<\/svg><\/div>/m) }
-        it { is_expected.to match(/<h1.*>This is a fixture<\/h1>/m) }
+        it do
+          is_expected.to have_tag('div', with: { class: 'plantuml' }) do
+            with_tag('svg')
+          end
+        end
+
+        it { is_expected.to have_tag('h1', text: 'This is a fixture') }
       end
     end
   end
diff --git a/spec/kramdown_html_spec.rb b/spec/kramdown_html_spec.rb
index 1bb874af..7c1bba6e 100644
--- a/spec/kramdown_html_spec.rb
+++ b/spec/kramdown_html_spec.rb
@@ -8,15 +8,13 @@
     let (:options) { { input: 'GFM' } }
 
     subject do
-      diagram = File.read(File.join(__dir__, 'examples', 'diagram.plantuml'))
+      diagram = File.read(File.join(__dir__, 'examples', 'network-diagram.puml'))
       document = "```plantuml\n#{diagram}\n```"
       Kramdown::Document.new(document, options).to_html
     end
 
     context 'clean' do
-      it {
-        is_expected.to include('class="plantuml">')
-      }
+      it { is_expected.to have_tag('div', with: { class: 'plantuml' }) }
     end
 
     context 'built-in theme' do
@@ -31,9 +29,7 @@
         }
       }
 
-      it {
-        is_expected.to include('class="plantuml theme-spacelab">')
-      }
+      it { is_expected.to have_tag('div', with: { class: 'plantuml theme-spacelab' }) }
 
       it 'has theme metadata', :debug do
         is_expected.to include("!theme spacelab")
@@ -55,9 +51,7 @@
         }
       }
 
-      it {
-        is_expected.to include('class="plantuml theme-c2a3b0">')
-      }
+      it { is_expected.to have_tag('div', with: { class: 'plantuml theme-c2a3b0' }) }
 
       it 'has theme metadata', :debug do
         is_expected.to include("!theme c2a3b0 from #{examples_dir}")
diff --git a/spec/none_s_spec.rb b/spec/none_s_spec.rb
new file mode 100644
index 00000000..42234b10
--- /dev/null
+++ b/spec/none_s_spec.rb
@@ -0,0 +1,27 @@
+# frozen_string_literal: false
+
+require 'kramdown-plantuml/none_s'
+
+describe Object do
+  describe '#none_s?' do
+    subject { value.none_s? }
+
+    context 'with invalid values' do
+      [{}, [], nil, '', '     ', 'a', '0', '1', 'true', 'false', 'nil', '[]', '{}'].each do |v|
+        context "'#{v}'" do
+          let (:value) { v }
+          it { is_expected.to be false }
+        end
+      end
+    end
+
+    context 'with valid values' do
+      ['none', '   none    ', 'NONE', 'NoNe', :none].each do |v|
+        context "'#{v}'" do
+          let (:value) { v }
+          it { is_expected.to be true }
+        end
+      end
+    end
+  end
+end
diff --git a/spec/options_spec.rb b/spec/options_spec.rb
index cc2d5791..f4228599 100644
--- a/spec/options_spec.rb
+++ b/spec/options_spec.rb
@@ -3,7 +3,7 @@
 require 'rspec/its'
 require 'kramdown-plantuml/options'
 
-Options = Kramdown::PlantUml::Options
+Options ||= Kramdown::PlantUml::Options
 
 describe Options do
   let(:hash) { {} }
diff --git a/spec/diagram_spec.rb b/spec/plantuml_diagram_spec.rb
similarity index 57%
rename from spec/diagram_spec.rb
rename to spec/plantuml_diagram_spec.rb
index b10151e3..93390df8 100644
--- a/spec/diagram_spec.rb
+++ b/spec/plantuml_diagram_spec.rb
@@ -1,20 +1,20 @@
 # frozen_string_literal: false
 
 require 'rspec/its'
-require 'kramdown-plantuml/diagram'
+require 'kramdown-plantuml/plantuml_diagram'
 
-Diagram = ::Kramdown::PlantUml::Diagram
+PlantUmlDiagram ||= ::Kramdown::PlantUml::PlantUmlDiagram
 
-describe Diagram do
-  plantuml_content = File.read(File.join(__dir__, 'examples', 'diagram.plantuml'))
+describe PlantUmlDiagram do
+  plantuml_content = File.read(File.join(__dir__, 'examples', 'network-diagram.puml'))
 
-  describe '#convert_to_svg' do
+  describe '#svg' do
     context 'gracefully fails' do
-      subject { Diagram.new(plantuml, Options.new).convert_to_svg }
+      subject { PlantUmlDiagram.new(plantuml, Options.new).svg.to_s }
 
       context 'with nil plantuml' do
         let(:plantuml) { nil }
-        it { is_expected.to be_nil }
+        it { is_expected.to be_empty }
       end
 
       context 'with empty plantuml' do
@@ -24,58 +24,42 @@
     end
 
     context 'successfully converts' do
-      before(:all) { @converted_svg = Diagram.new(plantuml_content, Options.new).convert_to_svg }
+      before(:all) { @converted_svg = PlantUmlDiagram.new(plantuml_content, Options.new).svg.to_s }
       subject { @converted_svg }
 
       it {
         is_expected.not_to include('No @startuml/@enduml found')
       }
 
-      it {
-        is_expected.to include('<ellipse')
-      }
-
-      it {
-        is_expected.to include('<polygon')
-      }
-
-      it {
-        is_expected.to include('<path')
-      }
-
-      it {
-        is_expected.to include('<div')
-      }
-
-      it {
-        is_expected.to include('</div>')
-      }
-
       it {
         is_expected.not_to include('<?xml version=')
       }
 
-      it {
-        is_expected.to include('class="plantuml"')
-      }
+      it do
+        is_expected.to have_tag('div', with: { class: 'plantuml' }) do
+          with_tag('ellipse')
+          with_tag('polygon')
+          with_tag('path')
+        end
+      end
     end
   end
 
   context 'fails properly' do
-    subject { Diagram.new(plantuml, options) }
+    subject { PlantUmlDiagram.new(plantuml, options) }
     let(:hash) { nil }
     let(:options) { Options.new(hash) }
 
     context 'with invalid PlantUML' do
       let(:plantuml) { 'INVALID!' }
 
-      its(:convert_to_svg) do
+      its(:svg) do
         will raise_error(Kramdown::PlantUml::PlantUmlError, /INVALID!/)
       end
 
       context ('with raise_errors: false') do
         let(:hash) {  { plantuml: { raise_errors: false } } }
-        its(:convert_to_svg) { will_not raise_error }
+        its(:svg) { will_not raise_error }
       end
     end
 
@@ -83,13 +67,13 @@
       let(:plantuml) { "@startuml\n@enduml" }
       let(:hash) { { plantuml: { theme: { name: 'xyz', directory: 'assets' } } } }
 
-      its(:convert_to_svg) do
+      its(:svg) do
         will raise_error(Kramdown::PlantUml::PlantUmlError, /theme 'xyz' can't be found in the directory 'assets'/)
       end
 
       context ('with raise_errors: false') do
         let(:hash) {  { plantuml: { raise_errors: false } } }
-        its(:convert_to_svg) { will_not raise_error }
+        its(:svg) { will_not raise_error }
       end
     end
   end
diff --git a/spec/plantuml_error_spec.rb b/spec/plantuml_error_spec.rb
index 247fc1fa..150fa005 100644
--- a/spec/plantuml_error_spec.rb
+++ b/spec/plantuml_error_spec.rb
@@ -4,17 +4,17 @@
 require 'kramdown-plantuml/options'
 require 'kramdown-plantuml/plantuml_error'
 
-Options = ::Kramdown::PlantUml::Options
-Diagram = ::Kramdown::PlantUml::Diagram
-PlantUmlError = ::Kramdown::PlantUml::PlantUmlError
-PlantUmlResult = ::Kramdown::PlantUml::PlantUmlResult
+Options ||= Kramdown::PlantUml::Options
+PlantUmlDiagram ||= Kramdown::PlantUml::PlantUmlDiagram
+PlantUmlError = Kramdown::PlantUml::PlantUmlError
+PlantUmlResult = Kramdown::PlantUml::PlantUmlResult
 
 describe PlantUmlError do
   describe '#initialize' do
     let(:plantuml) { 'some plantuml' }
     let(:options) { Options.new }
     let(:exitcode) { 1 }
-    let(:diagram) { Diagram.new(plantuml, options) }
+    let(:diagram) { PlantUmlDiagram.new(plantuml, options) }
     let(:result) { PlantUmlResult.new(diagram, '', stderr, exitcode) }
     subject { PlantUmlError.new(result) }
 
diff --git a/spec/plantuml_result_spec.rb b/spec/plantuml_result_spec.rb
index 89ae6bf0..2eb02cc7 100644
--- a/spec/plantuml_result_spec.rb
+++ b/spec/plantuml_result_spec.rb
@@ -9,7 +9,7 @@
     let (:stderr) { nil }
 
     subject {
-      diagram = ::Kramdown::PlantUml::Diagram.new("@startuml\n@enduml", Options.new)
+      diagram = ::Kramdown::PlantUml::PlantUmlDiagram.new("@startuml\n@enduml", Options.new)
       result = ::Kramdown::PlantUml::PlantUmlResult.new(diagram, '', stderr, exitcode)
       result.valid?
     }
@@ -46,7 +46,7 @@
 
   describe '#initialize' do
     subject {
-      diagram = ::Kramdown::PlantUml::Diagram.new("@startuml\n@enduml", Options.new)
+      diagram = ::Kramdown::PlantUml::PlantUmlDiagram.new("@startuml\n@enduml", Options.new)
       ::Kramdown::PlantUml::PlantUmlResult.new(diagram, stdout, stderr, exitcode)
     }
 
@@ -55,8 +55,12 @@
       let (:stdout) { 'some stdout' }
       let (:exitcode) { 1337 }
 
-      its(:diagram) {
-        is_expected.to be_a ::Kramdown::PlantUml::Diagram
+      its(:plantuml_diagram) {
+        is_expected.to be_a ::Kramdown::PlantUml::PlantUmlDiagram
+      }
+
+      its(:svg_diagram) {
+        is_expected.to be_a ::Kramdown::PlantUml::SvgDiagram
       }
 
       its(:stdout) {
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 1a38ad5f..789eb831 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require 'rspec-html-matchers'
+
 # This file was generated by the `rspec --init` command. Conventionally, all
 # specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
 # The generated `.rspec` file contains `--require spec_helper` which will cause
@@ -16,6 +18,8 @@
 #
 # See http://rubydoc.info/gems/rspec-core/RSpec/Core/Configuration
 RSpec.configure do |config|
+  config.include RSpecHtmlMatchers
+
   # rspec-expectations config goes here. You can use an alternate
   # assertion/expectation library such as wrong or the stdlib/minitest
   # assertions if you prefer.
diff --git a/spec/style_builder_spec.rb b/spec/style_builder_spec.rb
new file mode 100644
index 00000000..c3e1818c
--- /dev/null
+++ b/spec/style_builder_spec.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: false
+
+require 'rspec/its'
+require 'kramdown-plantuml/style_builder'
+
+StyleBuilder ||= Kramdown::PlantUml::StyleBuilder
+
+describe StyleBuilder do
+  subject { StyleBuilder.new }
+
+  context '[nil]' do
+    before(:each) { subject[nil] = '' }
+    its(:to_s) { is_expected.to eq '' }
+  end
+
+  context 'nil value' do
+    before(:each) { %i[width height style].each { |key| subject[key] = nil }}
+    its(:to_s) { is_expected.to eq '' }
+  end
+
+  context '[:width]' do
+    before(:each) { subject[:width] = '200px' }
+    its(:to_s) { is_expected.to eq 'width:200px' }
+  end
+
+  context '[:height]' do
+    before(:each) { subject[:height] = '200px' }
+    its(:to_s) { is_expected.to eq 'height:200px' }
+  end
+  context '[:width, :height, :style]' do
+    before(:each) do
+      subject[:height] = '200px'
+      subject[:width] = '1337px'
+      subject[:style] = 'border: 1px solid red; background-color: #ffffff;'
+    end
+
+    its(:to_s) { is_expected.to eq 'background-color:#ffffff;border:1px solid red;height:200px;width:1337px' }
+  end
+end
diff --git a/spec/svg_diagram_spec.rb b/spec/svg_diagram_spec.rb
new file mode 100644
index 00000000..df40c020
--- /dev/null
+++ b/spec/svg_diagram_spec.rb
@@ -0,0 +1,128 @@
+# frozen_string_literal: false
+
+require 'rspec/its'
+require 'kramdown-plantuml/svg_diagram'
+
+Options ||= Kramdown::PlantUml::Options
+SvgDiagram ||= ::Kramdown::PlantUml::SvgDiagram
+
+describe SvgDiagram do
+  describe '#initialize' do
+    context 'minimal diagram' do
+      before(:all) { @svg = Kramdown::PlantUml::PlantUmlDiagram.new("@startuml\n@enduml", Options.new).svg }
+      subject { @svg }
+
+      its(:width) { is_expected.not_to be_nil }
+      its(:height) { is_expected.not_to be_nil }
+      its(:style) { is_expected.not_to be_nil }
+    end
+
+    context 'with string options' do
+      before(:all) {
+        options = Options.new(plantuml: { width: '1337px', height: '1234px', style: 'border: 7px solid red' })
+        @svg = Kramdown::PlantUml::PlantUmlDiagram.new("@startuml\n@enduml", options).svg
+      }
+      subject { @svg }
+
+      its(:width) { is_expected.to eq '1337px' }
+      its(:height) { is_expected.to eq '1234px' }
+      its(:style) { is_expected.to eq 'border:7px solid red;height:1234px;width:1337px' }
+      its(:to_s) {
+        is_expected.to have_tag('svg', with: {
+          width: '1337px',
+          height: '1234px',
+          style: 'border:7px solid red;height:1234px;width:1337px'
+        })
+      }
+    end
+
+    context 'with integer options' do
+      before(:all) {
+        options = Options.new(plantuml: { width: 100, height: 200 })
+        @svg = Kramdown::PlantUml::PlantUmlDiagram.new("@startuml\n@enduml", options).svg
+      }
+      subject { @svg }
+
+      its(:width) { is_expected.to eq '100' }
+      its(:height) { is_expected.to eq '200' }
+      its(:style) { is_expected.to eq 'height:200;width:100' }
+      its(:to_s) {
+        is_expected.to have_tag('svg', with: {
+          width: '100',
+          height: '200',
+          style: 'height:200;width:100'
+        })
+      }
+    end
+
+    context 'with all none' do
+      before(:all) {
+        options = Options.new(plantuml: { width: 'none', height: 'none', style: 'none' })
+        @svg = Kramdown::PlantUml::PlantUmlDiagram.new("@startuml\n@enduml", options).svg
+      }
+      subject { @svg }
+
+      its(:width) { is_expected.to eq :none }
+      its(:height) { is_expected.to eq :none }
+      its(:style) { is_expected.to eq :none }
+      describe '#to_s' do
+        subject { @svg.to_s }
+        it { is_expected.not_to have_tag('svg[width]') }
+        it { is_expected.not_to have_tag('svg[height]') }
+        it { is_expected.not_to have_tag('svg[style]') }
+      end
+    end
+
+    context 'with all :none' do
+      before(:all) {
+        options = Options.new(plantuml: { width: :none, height: :none, style: :none })
+        @svg = Kramdown::PlantUml::PlantUmlDiagram.new("@startuml\n@enduml", options).svg
+      }
+      subject { @svg }
+
+      its(:width) { is_expected.to eq :none }
+      its(:height) { is_expected.to eq :none }
+      its(:style) { is_expected.to eq :none }
+      describe '#to_s' do
+        subject { @svg.to_s }
+        it { is_expected.not_to have_tag('svg[width]') }
+        it { is_expected.not_to have_tag('svg[height]') }
+        it { is_expected.not_to have_tag('svg[style]') }
+      end
+    end
+
+    context 'with :none width and height' do
+      before(:all) {
+        options = Options.new(plantuml: { width: :none, height: :none })
+        @svg = Kramdown::PlantUml::PlantUmlDiagram.new("@startuml\n@enduml", options).svg
+      }
+      subject { @svg }
+
+      its(:width) { is_expected.to eq :none }
+      its(:height) { is_expected.to eq :none }
+      its(:style) { is_expected.not_to be_nil }
+      describe '#to_s' do
+        subject { @svg.to_s }
+        it { is_expected.to have_tag('svg[style]') }
+        it { is_expected.not_to have_tag('svg[width]') }
+        it { is_expected.not_to have_tag('svg[height]') }
+        it { is_expected.not_to include 'width' }
+        it { is_expected.not_to include 'height' }
+      end
+    end
+
+    context 'fails properly' do
+      subject { SvgDiagram.new(result) }
+
+      context 'with nil result' do
+        let(:result) { nil }
+        it { expect { subject }.to raise_error(ArgumentError, 'plantuml_result cannot be nil') }
+      end
+
+      context 'result is not PlantUmlResult' do
+        let(:result) { '' }
+        it { expect { subject }.to raise_error(ArgumentError, "plantuml_result must be a #{Kramdown::PlantUml::PlantUmlResult}") }
+      end
+    end
+  end
+end
diff --git a/spec/theme_spec.rb b/spec/theme_spec.rb
index 58acb92f..4b6cd6d5 100644
--- a/spec/theme_spec.rb
+++ b/spec/theme_spec.rb
@@ -5,7 +5,7 @@
 require 'kramdown-plantuml/theme'
 
 Theme = Kramdown::PlantUml::Theme
-Options = Kramdown::PlantUml::Options
+Options ||= Kramdown::PlantUml::Options
 
 describe Theme do
   describe '#initialize' do