diff --git a/sphinx_simplepdf/builders/simplepdf.py b/sphinx_simplepdf/builders/simplepdf.py
index c4576dd..8167d6a 100644
--- a/sphinx_simplepdf/builders/simplepdf.py
+++ b/sphinx_simplepdf/builders/simplepdf.py
@@ -4,8 +4,6 @@
 import subprocess
 import weasyprint
 
-import sass
-
 from bs4 import BeautifulSoup
 
 from sphinx import __version__
@@ -52,53 +50,6 @@ def __init__(self, *args, **kwargs):
         }
         self.app.config.html_context["spd"] = debug_sphinx
 
-        # Generate main.css
-        logger.info("Generating css files from scss-templates")
-        css_folder = os.path.join(self.app.outdir, f"_static")
-        scss_folder = os.path.join(
-            os.path.dirname(__file__), "..", "themes", "simplepdf_theme", "static", "styles", "sources"
-        )
-        sass.compile(
-            dirname=(scss_folder, css_folder),
-            output_style="nested",
-            custom_functions={
-                sass.SassFunction("config", ("$a", "$b"), self.get_config_var),
-                sass.SassFunction("theme_option", ("$a", "$b"), self.get_theme_option_var),
-            },
-        )
-
-    def get_config_var(self, name, default):
-        """
-        Gets a config variables for scss out of the Sphinx configuration.
-        If name is not found in config, the specified default var is returned.
-
-        Args:
-            name: Name of the config var to use
-            default: Default value, if name can not be found in config
-
-        Returns: Value
-        """
-        simplepdf_vars = self.app.config.simplepdf_vars
-        if name not in simplepdf_vars:
-            return default
-        return simplepdf_vars[name]
-
-    def get_theme_option_var(self, name, default):
-        """
-        Gets a option  variables for scss out of the Sphinx theme options.
-        If name is not found in theme options, the specified default var is returned.
-
-        Args:
-            name: Name of the option var to use
-            default: Default value, if name can not be found in config
-
-        Returns: Value
-        """
-        simplepdf_theme_options = self.app.config.simplepdf_theme_options
-        if name not in simplepdf_theme_options:
-            return default
-        return simplepdf_theme_options[name]
-
     def finish(self) -> None:
         super().finish()
 
diff --git a/sphinx_simplepdf/themes/simplepdf_theme/__init__.py b/sphinx_simplepdf/themes/simplepdf_theme/__init__.py
index 9837ce8..4c985d1 100644
--- a/sphinx_simplepdf/themes/simplepdf_theme/__init__.py
+++ b/sphinx_simplepdf/themes/simplepdf_theme/__init__.py
@@ -1,23 +1,50 @@
 """Sphinx ReadTheDocs theme.
 From https://github.com/ryan-roemer/sphinx-bootstrap-theme.
 """
+import logging
 from os import path
 
+import sass
+from sphinx.application import Sphinx
 
 __version__ = '0.1.0'
 __version_full__ = __version__
 
+logger = logging.getLogger(__name__)
 
-def get_html_theme_path():
-    """Return list of HTML theme paths."""
-    cur_dir = path.abspath(path.dirname(path.dirname(__file__)))
-    return cur_dir
+
+def get_html_theme_path() -> str:
+    return path.abspath(path.dirname(__file__))
+
+
+def compile_css(app: Sphinx):
+    # Generate main.css
+    logger.info("Generating css files from scss-templates")
+    css_folder = path.join(app.outdir, f"_static")
+    scss_folder = path.join(get_html_theme_path(), "static", "styles", "sources")
+
+    sass.compile(
+        dirname=(scss_folder, css_folder),
+        output_style="nested",
+        custom_functions={
+            sass.SassFunction(
+                "config",
+                ("$a", "$b"),
+                app.config.simplepdf_vars.get
+            ),
+            sass.SassFunction(
+                "theme_option",
+                ("$a", "$b"),
+                app.config.simplepdf_theme_options.get
+            ),
+        },
+    )
 
 
 # See http://www.sphinx-doc.org/en/stable/theming.html#distribute-your-theme-as-a-python-package
-def setup(app):
-    app.add_html_theme('simplepdf_theme', path.abspath(path.dirname(__file__)))
-    # app.add_css_file('styles/main.css')
+def setup(app: Sphinx):
+    app.add_html_theme('simplepdf_theme', get_html_theme_path())
+    app.connect('builder-inited', compile_css)
 
     return {
         "parallel_read_safe": True,