diff --git a/src/pyj/book_list/theme.pyj b/src/pyj/book_list/theme.pyj
index 8a3c6e985f..8a4437234e 100644
--- a/src/pyj/book_list/theme.pyj
+++ b/src/pyj/book_list/theme.pyj
@@ -7,42 +7,54 @@ LIGHT = '#F6F3E9'
 LIGHT_DARKER = '#b6b3a8'
 LIGHT_GRADIENT = 'linear-gradient(to bottom, {}, {})'.format(LIGHT, LIGHT_DARKER)
 
+DEFAULT_COLORS = {
+    # General colors
+    'window-background': LIGHT,
+    'window-background2': LIGHT_DARKER,
+    'window-foreground': DARK,
+    'window-error-foreground': 'red',
+    'window-hover-foreground': 'red',
+
+    # Top bar specific colors
+    'bar-background': DARK,
+    'bar-foreground': LIGHT,
+    'bar-highlight': 'yellow',
+    'heart': '#B92111',
+
+    # Item list colors
+    'list-hover-background': DARK,
+    'list-hover-foreground': LIGHT,
+
+    # Tree colors
+    'tree-highlight-item': LIGHT_DARKER,
+
+    # Button colors
+    'button-start': DARK,
+    'button-end': '#49423B',
+    'button-text': LIGHT,
+
+    # Dialog colors
+    'dialog-background': LIGHT,
+    'dialog-background-image': LIGHT_GRADIENT,
+    'dialog-foreground': DARK,
+}
+
+DEFAULT_SIZES = {
+    'title': '1.4rem',
+    'item-list-title': '1.1rem',
+    'item-list-subtitle': '0.8rem',
+}
+
+DEFAULT_FONTS = {
+    'main': 'sans-serif'
+}
+
 def get_color(name):
-    return {
-        # General colors
-        'window-background': LIGHT,
-        'window-background2': LIGHT_DARKER,
-        'window-foreground': DARK,
-        'window-error-foreground': 'red',
-        'window-hover-foreground': 'red',
-
-        # Top bar specific colors
-        'bar-background': DARK,
-        'bar-foreground': LIGHT,
-        'bar-highlight': 'yellow',
-        'heart': '#B92111',
-
-        # Item list colors
-        'list-hover-background': DARK,
-        'list-hover-foreground': LIGHT,
-
-        # Tree colors
-        'tree-highlight-item': LIGHT_DARKER,
-
-        # Button colors
-        'button-start': DARK,
-        'button-end': '#49423B',
-        'button-text': LIGHT,
-
-        # Dialog colors
-        'dialog-background': LIGHT,
-        'dialog-background-image': LIGHT_GRADIENT,
-        'dialog-foreground': DARK,
-    }[name]
+    return DEFAULT_COLORS[name]
 
 def get_font_size(name):
-    return {
-        'title': '1.4rem',
-        'item-list-title': '1.1rem',
-        'item-list-subtitle': '0.8rem',
-    }[name]
+    return DEFAULT_SIZES[name]
+
+def get_font_family(name):
+    name = name or 'main'
+    return DEFAULT_FONTS[name]